Two rooms cap the Saturday. The frames can absorb more children, but a party needs a table, so the number of rooms multiplied by the slots is the real ceiling on the best day of the week.
Numbers change on the Thursday. Catering, party bags and staffing all follow a headcount that is confirmed late, so a booking record that cannot be updated cleanly produces either waste or a shortage.
Capacity is not a comfort figure. A maximum number of children in a session exists for evacuation and supervision reasons, and exceeding it on a wet Saturday is the kind of decision that ends badly.
A party allergy list has to reach the kitchen. Fifteen children with three allergies between them is normal, and that information has to travel from the booking form to whoever puts food on the table.