Even a perfect kitchen needs the same minutes every time
A hundred guests do not receive their meals at once. Food travels from kitchen to plate to table in a sequence, and that sequence has a pace the schedule cannot override.
The standard working figure in professional catering is roughly two minutes per table for a served course — and that assumes a well-staffed room, no obstacles, and plates that left the pass hot and ready at the same moment. Twenty tables means forty minutes between the first plate landing and the last one. Guests seated early watch their food arrive; guests at the far end of the room watch theirs not arrive. The meal has started before it has started.
This is why the run-sheet entry "main course served" is not a moment but a range, and why the kitchen needs to know the cover count, the table layout, and the direction of service before the day — not the morning of.
Clearing follows the same logic in reverse, and clearing is slower. Guests finish at different times. A table that is still eating must be skipped and returned to. A hundred covers, two courses, and a dessert that requires a clean table: the arithmetic is simply there, and wishing otherwise does not shorten it. Where the meal service sits in the afternoon shapes everything that follows — speeches, first dance, the moment the bar opens properly. Compress the time allocated and the kitchen is not the only thing that suffers; the whole afternoon loses an hour before anyone has noticed it happening.
The practical adjustment is simple, if unglamorous: add the real service time, add the real clearing time, and only then write in the next item on the sheet. Caterers will tell you how long they need if you ask. The number they give is usually honest and usually ignored. Take it seriously and the afternoon runs; discount it and you spend the rest of the day chasing buffer that was never there.