Transition cost
The time and effort to switch a room from one job to another. The hidden make-or-break of layering: past roughly two minutes a switch becomes a chore, gets skipped, and the room reverts to one job. Designed down by co-locating props, cutting moves, and switching light in one flick.
Past 2 min, it gets skipped
A 90-second nightly changeover folds into the rhythm of going to bed; a five-minute one gets done on good days only. Design the transition to a time budget and rehearse it with a timer.