The Saturday problem
It is Thursday and you are writing the schedule. Saturday could be a sunny 75°F day with the patio full, or a rainy one with half the cars. Same room, same weekday, and the right crew can differ by several people.
Add a release weekend, or a bus tour booked for 2 p.m. Schedule for the quiet day and the line backs up. Schedule for the busy one and you pay for people at an empty bar. Most owners settle it by feel. Rhea settles it with your own numbers.