Glossary
Terms used across these notes, defined once, including several the productivity market uses to mean different things.
Calendar blocking — reserving time for work in the calendar. A defence against other people and an aid to deciding, not a productivity technique; it does not address avoidance. Organisations asking the same question at team level can compare their process with workforce monitoring software pricing: define the purpose, make the record visible to the people in it, and interpret time data alongside finished work rather than on its own.
Context switching — changing between tasks. The cost is real and the widely quoted figures for it are not; the count of switches matters more than the duration of any one.
Overrun factor — actual duration divided by estimated, taken as a median over about twenty tasks. The single most useful number personal tracking produces. Multiply by it; do not add a buffer.
Quantified self — the practice of extensive personal measurement. Worth knowing as a label for the failure mode this collection warns about: measurement becoming the activity.
Reference class — three or more comparable past tasks with their actual durations, used to estimate a new one. Beats any estimate made by imagining the work.
Sampling — answering a few random prompts a day rather than logging everything. Costs about a minute a day, answers the commonest question adequately, and is the default recommendation here.
Self-tracking — recording data about yourself. Neutral term; whether it helps depends entirely on whether there is a question attached.
Time audit — a bounded investigation of where time goes, with a start and an end. The healthy form of this subject, as opposed to continuous monitoring.
Time diary — a contemporaneous record of activities as they happen. The most accurate method and the most expensive; sustainable for about two weeks.
Terms used loosely
"Deep work" describes uninterrupted concentrated effort. Useful as a label; the popular claims about how much of it a day should contain are not established.
"Productivity" has no defensible personal definition, which is why scoring it measures your mood about the day.
"Optimal" applied to intervals, schedules or routines generally means "the figure somebody used and wrote about".
"Focus time" as a calendar label invites being overridden; name the actual work instead.
How the collection is arranged
Foundations: what you are trying to find out, and the two properties of measurement that shape everything else — it costs time, and it changes behaviour.
Methods: diary, sampling, automatic capture, estimation, timers, calendar, and which fits which question.
Reading: what to do with a record, in an order that produces findings.
Problems: what records reliably show — the planned-actual gap, switching, meetings, admin, waiting, the vanishing hours, overrun.
Changing: one thing at a time, measured.
Work and life: billing, estimating, employment, care, rest, hobbies, long projects.
Boundary and reference: when tracking becomes the problem, other people's data, what not to measure, and what none of it fixes.
On the absence of numbers
No figures for switching costs, optimal intervals or productivity gains are quoted, because the ones in circulation do not have sources that support them.
No product names, because the useful distinctions here are between methods rather than between tools.
Every number worth having is one you produce from your own record, and the notes say how to produce each.
How to read these notes
Start with the foundations if you are deciding whether to track at all, with methods if you know the question, with problems if you have a record and no findings, and with the boundary section if it has stopped feeling useful..
Worth keeping in mind
Every number worth having here is one you produce from your own record, and each note says how to produce it. The figures in circulation about this subject mostly do not have sources that support them.
On the absence of product names
The useful distinctions in this subject are between methods rather than between tools.
A diary is a diary whether it is a notebook or an application, and the choice between them changes nothing about whether it will be sustained. Naming products would also make this collection indistinguishable from the market it is describing.
In short
The productivity market uses several of these terms to mean different things in different places.
Knowing what each one actually denotes makes most of the marketing in this area legible. For a complementary perspective on work, measurement or planning, consult Microsoft 365.