Book the time for the boring fix before the week fills
Reserving capacity for maintenance before commitments are made is the only form of slack that survives contact with a deadline, and a team at full utilisation cannot adopt any other control on this site.
Do this firstNothing. This is a place to start.
Capacity taken off the top, before planning, in a form somebody would have to argue to remove.
This is the highest-cost control here and the one least likely to be within the reader’s gift, which is why it is stated plainly rather than dressed up. Every other control on this site costs something now and pays later. A team with no slack can only take actions that pay immediately, so it cannot start — and the correct move is not to adopt six things badly but to buy the room for one.
The decoy
A rule that engineers may spend 20% of their time on maintenance. Unbooked time is not slack; it is the first thing that gets spent, and it is spent every week by whatever is most urgent.
Evidence
- The Cost of Interrupted Work: More Speed and Stress — I"people completed interrupted tasks in less time with no difference in quality" — subjects compensated by working faster — but stress and frustration were significantly higher in both interruption conditions than baseline. The cost of interruption showed up in the human, not in the output.
- An Empirical Study of WIP in Kanban Teams — II"WIP correlates with lead time; that is, lower WIP indicates shorter lead times, which is consistent with claims in the literature" — direct production-data support for the queueing mechanism the slack argument rests on.
Last reviewed 2026-08-19.