Project buffer: where to put it, and how to track it
A buffer hidden in every task disappears without anyone noticing. An explicit buffer, placed before the milestones that matter, tells you at any moment how much margin is left.
October 21 version
3 of 3 d left
Today
0 of 3 d left · consumed by the new site preparation (+3 d)
Production restart : unchanged
Everyone builds in margin. Most often, each person quietly adds it to their own tasks: a day here, two there. The result: the margin exists, but nobody knows where it is, or how much is left.
Hidden margin gets used up silently
A task padded by two days often ends up using them, even when it did not need them. Work expands to fill the time available. The margin disappears, and the schedule keeps no trace of it.
An explicit buffer, before the milestone
It is better to estimate tasks as tightly as possible and gather the margin into a visible buffer, placed just before the milestone that matters. In our relocation example, a 3-day buffer precedes the production restart.
Track how much buffer is consumed
When the new site preparation falls 3 days behind, reassembly and trials slip by as much. The restart milestone does not move: the buffer absorbed everything. The schedule then says two true things at once: the objective holds, and there is no margin left.
It is that second piece of information that matters in a steering committee. A milestone held with an intact buffer and a milestone held with an exhausted buffer are not the same situation.
Key points
- estimate tasks tightly, with no hidden margin;
- place an explicit buffer before every important milestone;
- track how much is left, not just the milestone date.