You could need to optimize the spending of your time for professional or personal activities. I am going to explain what means to me the time, and how you can manage it. I have been inspired by my knowledge, experiences, readings, and listenings, but it is my personal version of time management between math, physics, management, philosophy, and operational research. Without giving a lot of details, time management is also linked to the agile methodologies that are one implementation, like Scrum, Kanban, or Pomodoro.

The time management is the science of the usage of time, a possible definition could be the process of planning and exercising conscious control of time spent on specific activities, especially to increase effectiveness, efficiency, and productivity.

The way you can use your time depends on a lot of things, among others, there are your:

context:
- Which resources do you have (knowledge, time, energy, money …)
- What are your features (skills, experiences, character traits …)
- What are your constraints (costs, exigencies, …)
projection:
- What you want to do (ambitions, preferences, choices …)
- What are your goals (objectives, key results, tasks, sub-tasks, projects, missions …)
strategy:
- How do you organize your activities (priorities, hierarchies, dependencies, sizing, partitioning …)
analysis:
- How you know yourself (strong points, weak points, personal will, and effort …)
- How you have a projection & strategy coherent of yourself (clairvoyance, honesty, realism …)
- How you receive a critical opinion positive or negative on yourself (feedback, auto-introspections, questionings, doubts…)

Time Definition

With the meta-physique considerations, the time has wondering features: universal, continuous, unlimited, non-renewable, solid (incompressible/no expansible), perpetually self-generated, no accumulative. Focus is on the timescale of our human life. These features are immutable, or more precisely their changes are negligible. But we can interpret the time differently.

Here I am going to interpret the time like a quantizable object with an arbitrary window in the past, present or future. The present moment is seen like a progressive cursor representing a dynamic instant on the timeline. This present instant plays the role of an irreversible transformer altering the future into the past. The duration of an event is the length of a windows time delimited by 2 instants where the event began and finished. For the following, when I speak about time, I refer to these sliding windows.

The time

is one of our most valuable resources, for me more important than knowledge, money or energy, because all ones depend on time.

It is important to distinguish the absolute time, and the subjective time. The quantity of elapsed time to carry out an activity can be viewed and interpreted subjectively. The same quantity of time measured objectively in seconds could be lived differently by 2 different people esteemed like short or long. Take into account this subjectivity, because time management is more relevant if it is applied individually with your sensibility.

For example, a sharp mind in a particular situation will have the feeling of life in accelerated time by interacting with a less sharp mind, because he compares his thinking speed to that of his interlocutor, and this one is faster, and reciprocally. Another example is when you are doing a passionate activity. The time seems to go faster, because you forget the feeling of elapsed time, and inversely with the boredom.

The absolute time allows you to compare the duration between 2 activities objectively, but when you want to organize or optimize your time, you need to adjust your efforts with your personal consideration of an elapsed time for a given activity. The elapsed time can be interpreted as a sum of done activities. The unit measure of an activity is subjective, and could be called weight, where mixed the quantities of used resources to do the activity (for example the quantities of time, energy, or money). Here more the activity has a light color, the more the activity has a lightweight:

The time could be considered as a quantity of spent resources during a duration (itself in another meaning) to do activities now. So the quantity of available time at your disposition does not respect the time features mentioned previously, it is:

personal: you have a personal context and subjective time
discrete: you have a minimum time of reactivity for your frequency sample to measure the elapsed time
limited: you have a life length and resources which are finite
renewable: you can renew some activities in the future
compressible/expansible: you feel elapsed time differently for a given activity in function of time
occasionally generated by you: you make your choices, and your organization to free of time
cumulative: we interpret the time with a quantity now, not only an instant

But the quantity of time is always available immediately.

Concepts

We defined several ways to conceptualize the time, here I can define more precisely the other concepts of time management like the effort and the optimization.

The effort to do an activity is like the way of consummation of a number of resources. Your resources are renewed perpetually and have a potential, the activity has also a potential. You need to create a resource flow, called the intensity of the effort, to do the activity. The awareness to practice an extreme effort in quantity (too much or too few) or quality (too easy or too difficult) slows down the feeling of elapsed time and extends the time. This reduces your endurance in this activity. But the practice and the training allow you to reduce the feeling of effort, you consume less and/or have more resources.

It is important to observe that the optimization of the time usage is in fact the optimization of future projection of the productivity of an activity on a time range. This optimization is under constraints and depends on objectives, called also goals. To achieve these goals one of the available resources to use and save is time.

I use several concepts above without defining them, here is a summary:

Goal: definition of result(s) that you want to get, called also objective.
Task: definition of action(s) that you need to achieve a goal.
Activity: execution of task(s) over time.
Productivity: a measure of your performance (that is a combination of effectiveness and efficiency) of your activities.

Optimization Model

The time management can be seen in the modeling of an objective function to optimize. The model of this objective function is fixed by the definition of your goals (split into tasks) and of the execution plan. Then its optimization is determined by the duality between the minimization of the cost of executions and the maximization of quality of got results for a set of tasks.

In mathematics terms, that is to say optimize the objective function $g \circ f$ on a set of tasks $\bigcup x \subset X$ where:

\[f: X \rightarrow \mathbb{R}^+ \times \mathbb{R}^+ \quad x \mapsto f(x) = (c(x), q(x))\] \[g: Img(f) = \{\,f(x)\,|\,x \in X \} \subset \mathbb{R}^+ \times \mathbb{R}^+ \rightarrow \mathbb{R}^+ \quad y \mapsto g(y) = g(f(x)) = g(c(x), q(x))\]

$c$ is the cost function of executions
$q$ is the quality function of got results
$f$ is the productivity function in terms of efficiency and effectiveness
$g$ is a trade-off function between the minimization of the cost $c$ and maximization of the quality $q$ on subset of $X$

Objective function is a trade-off: cost vs quality of
a set of tasks — Objective function is a trade-off: cost vs quality of a set of tasks

But the stability, the evolution of the objective function depends on your regularity, your implication, and your progress.

The functions $c$ and $q$ are often linked, and it influences generally each one negatively for the optimization: reducing the cost reduces the quality, and increasing the quality increases the cost. While our optimization consists in reducing the cost, being efficient, and increasing the quality, to be effective. It is often more performant to be firstly effective, than efficient for a given task. Learning to do correctly a task before doing it faster. But it is clear, that being effective and efficient (at the same time and in good proportion) is the final goal for each task.

You can do an analogy with the machine learning algorithm. The execution plan is your model owning hyper-parameters, the tasks are rows of your dataset (training, validation, test) and the maximization of the objection function is the step of learning. With experience in an execution plan, you can predict the speed of execution and the quality of results.

Methodology

After having modeled and defined the concepts of time management, I am interested here by applying it in practice through a methodology. Firstly, even if you can model the time management, in my point of view it is an empirical science. That is to say, you need a methodology to test it, and your knowledge about this science will be provided by your experiences and your observations.

Here the main considered resource is the time, but in practice, the methodology could be more complex you could consider other inter-dependent resources to spend like money or energy.

Context

You need to list and put into perspective your resources, your skills, and your constraints.

Projection

After you need to define what you want to do and build your goals each one with a dateline. Do a first pass of the following section strategy applied to your goals (replace activities with goals). Once your goals are partitioned, hierarchized, sized, prioritized, and sequenced. Your destructed goals should now fill in a coherent structure. Then split each goal into tasks. You can repeat this operation to split each task into smaller activities to pass from a macro timescale to a micro timescale.

Strategy

The strategies are the fact to structure your activities to reach out.

Partition your activities

Partition your activities which have the same type in independent class between them the more possible. Of course, the content of each partition is subjective for some activities, you can classify your activities into these partitions differently in the function of your sensitivities and interests. You can already give an important weight to each partition.

Organize into a hierarchy your activities

Here the goal is to estimate roughly the weight of an activity to have its order of magnitude.

Each goal should be realistic, reachable, measurable with success keys, and sized in difficulty and required time to achieve it. You can play on several scales for your future projections: very long term, long term, middle term, short term, and very short term.

Size your activities

Now you can size more precisely each task. You can measure absolutely if it is complicated, you can also measure relatively the ones in relation to the other ones. You need to choose the unit of the * weight* of your activity.

Organize the interactions of activities

You need to build a dependency graph of each activity to see if an activity depends on other one(s).

Your dependency graph must be a set of acyclic graphs.

Prioritize your activities

After you need to rank your activities which ones are the most important ones:

Sequence your activities

It is you build your plan of execution by sequencing each activity by respecting the previous steps and your other constraints:

You can also optimize these sequencing.

Auto-analysis

Now you can execute your plan. But you need to monitor it, have logs, metrics, and traces, and have dashboards to visualize it. You need to do regular retrospectives and plans. Respectively adjust your strategy in the function of time, and continue to converge to the filling of your goals. Then define new goals or delete goals in order to avoid the shortage of tasks, the overload, or the accumulation of deprecated goals. Then you need to measure your KPI and your productivity. You need to have a feedback loop to build your virtuous circle, and iterate on it.

For Example

Are you a student, a worker, or a retiree? Take the example of a worker, more precisely a professional software engineer full-time working exclusively for a unique company at the beginning of their career. By hoping, that it matches your auto-introspection, else the following could help you to do the same thing for your personal context. I give you here only a partial overview of how it can be done, this example is not necessarily my real usage of my personal time.

I analyze my resources, my constraints, and my features (hard skills and soft skills, …).

Above all, I define what I want to do and my ambitions: following conferences, coding an open-source project, having a side project, becoming a speaker, losing weight, finishing TV series, reading books, following training, giving courses … Each goal should be precise, measurable, and reachable.

I split my activities into 3 partitions:

Life activities: required vital, society or community activities
for example sleep, eat, wash, practice a physical activity, interact with your environment, do the housework, pay the taxes, see your friends …
Work activities: required activities for your job
for example commute, work, do brainstorm, code, participate in a meeting, take a break …
Personal activities: spare and free activities
for example: practice its development personal, relaxation …

I focus on the life activities that compose my lifetime. I let on side work and personal activities, it is the principle.

For example, for the different timescales, I take long: ~hour and short: ~minute. I try to evaluate the time of each life activity:

sleeping: 7 hours per day
washing: 2 times 3 minutes per day for teeth and 15min per day for body
eating: 2 times 20 minutes per day for lunch and dinner with 10 minutes per day for the breakfast
seeing friends: at least one time per week for several hours
practicing sport: 3 hours per week
doing the other tasks: several hours per week (taking out the trash, preparing the meals, doing housework, shopping, do-it-yourself …)

These activities are not really dependent and with the same priority for me. Now I sequence them for each period of a day and of a week.

I have a calendar where I can monitor each timescale and put my tasks, a weekly planning for my datelines, and a to-do list for daily tasks.

Now I redo the same things for my personal activities, and my work activities to finish the management of my time.

Go Further

This article is only an introduction to time management applied to oneself by oneself. But the situation can be more complex. For example, if you think the time management for other people, if you are:

Tech/Team/Dev Leader for a team composed of a group of people
Tech/Project Manager/Director for a department composed of a group of teams
CTO for a R&D pole composed of departments
CEO for a company or a group of companies …

It requires delegating tasks, understanding the personal context of other people, and driving the time management for a group of people at different scales. These organizations can have different structures and different stakes. For it, you must redefine the time management to resolve your new needs for yourself and for other people.

References

MALABOU, Catherine. Le Temps. Hatier, 2019. 80 pages. ISBN: 2-218-71678-X.
Saint-Augustin. Les Confessions. 4 BC. Book XI.
KLEIN, Etienne. Les tactiques de Chronos. Flammarion, 2009. 224 pages. ISBN: 978-2-0812-2305-9.
HAWKING, Stephen. A Brief History of Time. Bantam Book, 2011. Chapter 2: Space and Time. 23 pages. ISBN: 978-0-857-50100-4.
VANDENBERGHE, Lieven. Convex Optimization. Cambridge University Press, 2009. Chapter 1: 16 pages. ISBN: 978-0-521-83378-3.
WINSTON, Wayne L.. Operations Research. Thomson Brooks/Cole, 2004. Chapter 1: 12 pages. ISBN: 0-534-38058-1.
MURPHY, Kevin P.. Machine Learning: A probabilistic Perspective. The MIT Press, 2012. Chapter 1: 24 pages. ISBN: 978-0-262-01802-9.
SUTHERLAND, Jeff. SCRUM. Business Books, 2014. 248 pages. ISBN: 978-1-847-94108-4.
ANDERSON, David J. Kanban: Successful Evolutionary … Blue Hole Press, 2010. 278 pages. ISBN: 978-0-9845214-1-8.
CIRILLO, Francesco. The Pomodoro Technique. 2018. 160 pages. ISBN: 1524760706.
OHNO, Taiichi. Toyota Production System. Synermage, 2020. 150 pages. ISBN: 106992329X.
New York University. Time Management. NYC, January 2023. Link
KOLMAR, Chris. Efficiency vs Effectiveness. Zippia, April 2021. Link