The Question Nobody Asks: At What Granularity Should You Track Time?
When an architecture firm or engineering office decides to implement time tracking, the discussion usually focuses on the "what" (which projects, which phases) and the "who" (which team members). But a fundamental question is almost always overlooked: at what precision should you log your time?
In practice, granularity is rarely a deliberate choice. It follows from the tool being used. With an Excel file, you check off full hours. With a timer, you track minutes. With a free-form field, everyone does it their own way.
Yet this seemingly trivial parameter has a considerable impact on two critical dimensions:
- Data quality collected -- and therefore the reliability of the decisions drawn from it.
- Adoption rate by teams -- because an entry process that's too constraining is an entry process that gets abandoned.
Too Fine (1 Minute): The Micro-Management Trap
The idea seems appealing: if we track every minute, we'll have the most precise data possible. In reality, minute-level granularity creates more problems than it solves.
The permanent timer syndrome. When the timer runs continuously, team members develop a form of anxiety. Every interruption -- a phone call, a colleague's question, a coffee break -- becomes a source of stress. "Did I start the timer? Did I forget to stop it?"
False precision. Was it really 7 minutes or 12? The difference is insignificant for managing a project, but the system demands an exact answer. You end up inventing numbers to satisfy the tool.
The hidden cost. The time spent managing timers, correcting oversights, and adjusting errors quickly exceeds the time saved by the additional "precision." That's the measurement paradox: the finer you measure, the more the measurement itself becomes a burden.
Key takeaway: In most agencies that adopt minute-level tracking, utilization rates drop drastically after two to three weeks. The tool is perceived as a surveillance instrument, not a management tool.
Too Coarse (1 Hour): The Precision Loss That's Expensive
Conversely, logging time in one-hour blocks seems simple and quick. It's the default mode for most Excel files. But this simplicity comes at a price.
Systematic rounding effect. A 1h10 task becomes 2h. A 45-minute exchange becomes 1h. And a half-hour of admin disappears entirely because "it's not enough to warrant a line."
Annual drift. Rounding after rounding, the gap between actual time and declared time widens. Over a full year, the distortion commonly reaches 15 to 20% of total time. Enough to skew a profitability calculation or mask a budget overrun.
The impossibility of fine-grained decisions. With one-hour blocks, you can't distinguish a DCE phase that consumed 60% of its budget from an APS phase at 40%. Everything drowns in numbers too coarse to guide a decision.
Key figure: A project manager architect who logs in one-hour blocks overestimates their declared time by an average of 1 to 1.5 hours per day, equivalent to 250 to 350 phantom hours per year.
15 Minutes: The Sweet Spot for Services Companies
Between the anxiety-inducing minute and the imprecise hour, the 15-minute slot emerges as the best compromise for project management professions.
Here's how the same typical day looks depending on the chosen granularity:
| Actual activity | Actual duration | 1-min entry | 15-min entry | 1-hour entry |
|---|---|---|---|---|
| Project A meeting | 1h05 | 1h05 | 1h15 | 2h |
| Project B design | 2h20 | 2h20 | 2h15 | 2h |
| Emails / coordination | 0h40 | 0h40 | 0h45 | 1h |
| Project C site visit | 1h45 | 1h45 | 1h45 | 2h |
| Visit report | 0h50 | 0h50 | 0h45 | 1h |
| Admin / HR | 0h35 | 0h35 | 0h30 | 0h (undeclared) |
| Total declared | 7h15 | 7h15 | 7h15 | 8h |
The finding is telling. The 15-minute entry produces a total almost identical to reality, with negligible per-line differences (+/- 10 minutes maximum). The hourly entry, on the other hand, accumulates roundings and inflates the total by 45 minutes -- while making admin time disappear entirely.
Why 15 minutes works so well:
- Fine enough to capture significant differences. A 1h15 meeting isn't the same as a 2h meeting. In 15-minute blocks, the distinction is preserved.
- Simple enough not to become a burden. No timer needed. At the end of the day, you can easily reconstruct your 15-minute slots.
- Aligned with billing conventions. Many firms and engineering offices already bill in 15-minute increments. The entry directly matches the economic logic.
A "pill" entry system makes this granularity even smoother: each click represents a 15-minute block, and it takes just a few seconds to reconstruct your day. No long form, no mental math -- you click, it's done. Discover how this approach works in practice.
Concrete Example: A Typical Day for a Project Manager Architect
Let's take the day of Sophie, a project manager architect at a 15-person firm.
Morning:
- 8:30am - 9:45am: coordination meeting for a residential project (PRO phase)
- 9:45am - 10:00am: emails and supplier follow-ups
- 10:00am - 12:00pm: design work on an ongoing competition
- 12:00pm - 12:30pm: lunch with a structural engineer (informal project discussion)
Afternoon:
- 1:30pm - 3:15pm: site visit
- 3:15pm - 4:00pm: writing the visit report
- 4:00pm - 4:30pm: phone call with the residential project client
- 4:30pm - 5:00pm: admin (expense reports, next week's planning)
Here's what these 8 hours look like at each granularity:
| 1-min entry | 15-min entry | 1-hour entry | |
|---|---|---|---|
| Residential project coordination | 1h15 | 1h15 | 1h |
| Emails / follow-ups | 0h15 | 0h15 | 0h (lost) |
| Competition design | 2h00 | 2h00 | 2h |
| Project lunch (informal) | 0h30 | 0h30 | 1h |
| Site visit | 1h45 | 1h45 | 2h |
| Visit report | 0h45 | 0h45 | 1h |
| Client call | 0h30 | 0h30 | 1h |
| Admin | 0h30 | 0h30 | 0h (lost) |
| Total | 7h30 | 7h30 | 8h |
| Gap vs. reality | 0 min | 0 min | +30 min |
At the minute level, the result is exact -- but at what cost in terms of entry effort and mental load? At 15 minutes, the result is just as reliable, for an entry that takes less than two minutes at day's end. At the hour level, you lose 30 minutes of net visibility, and two entire categories (emails, admin) disappear from the radar.
Impact on Data Quality: When Granularity Changes Decisions
Granularity isn't just a comfort question. It directly determines the quality of management decisions.
With one-hour blocks, a project often seems "on track." Administrative time and coordination are under-declared, which artificially inflates the productive share. The project manager believes they have more margin than they actually do. Management ratios are skewed.
With 15-minute blocks, hidden time resurfaces. You discover that inter-discipline coordination consumes 20% of time on a complex project. That admin represents 45 minutes per day per person. That the DET phase systematically overruns its budget by 15%.
These insights change decisions:
- Staffing: you anticipate the need for reinforcement on identified time-consuming phases.
- Budgets: you adjust fees with full knowledge, project after project.
- Amendments: you have factual data to justify a fee amendment to the project owner, instead of negotiating by "gut feel."
Key takeaway: The 15-minute granularity isn't a default compromise. It's a methodological choice that maximizes the ratio between data quality and entry effort. For architecture firms and engineering offices, it's the level of precision that transforms time tracking into a genuine management tool.
The right question isn't "how much time do we spend?" but "do we have the right precision to decide?" In the vast majority of cases, the answer is two digits: 1 and 5.