Plan from your average capacity, not your best day — five days of measurement is enough
After measuring five days of actual focused work time, use the daily average (not the best day or hoped-for number) as your baseline planning capacity for all future scheduling decisions.
Why This Is a Rule
Most people plan their days based on their peak capacity: "I can do 6 hours of deep work when I'm really focused." This is planning from the best case rather than the average case, and it guarantees chronic under-delivery. Your best day is your best day — it's not your typical day, and planning as if every day is your best day means most days fall short.
Five days of measurement produces a baseline average that accounts for normal variation. If you tracked 5, 3, 4, 6, and 2 hours of focused work, your average is 4 hours — not the 6 you hit on your best day, and not the 8 you hope for. Four hours is your planning capacity: the number you use when scheduling, committing, and estimating.
The average is the right statistic because it's the expected value — the number you'll hit on a typical day. Planning from the average means roughly half your days exceed the plan (buffer accumulates) and half fall short (buffer is consumed). Over time, these average out. Planning from the peak means nearly every day falls short, and you accumulate deficit instead of buffer.
When This Fires
- Setting up a capacity-based planning system for the first time
- After suspecting your planning capacity is unrealistic
- When chronic under-delivery suggests a mismatch between planned and actual capacity
- Recalibrating after a major life or work change (new job, new schedule, new responsibilities)
Common Failure Mode
Using the best day as the baseline: "I did 6 hours on Tuesday, so I should be able to do 6 hours every day." You can't — Tuesday was an outlier. Using the hoped-for number is even worse: "I should be able to do 8 hours of focused work." You've never measured 8, but it feels like what a productive person "should" do. Plan from data, not aspiration.
The Protocol
(1) For five consecutive workdays, track actual focused work time (deep work only, not meetings or admin). Use a timer or time-tracking app for accuracy. (2) Calculate the daily average. (3) Use this average as your planning capacity for all future scheduling: sprint commitments, project estimates, daily plans. (4) Do not adjust upward because it "feels low" — if it feels low, that's your aspiration talking, not your data. (5) Re-measure quarterly or after significant schedule changes.