20,000 in one night?
Why was 20k so hard to make for a high class restaurant like that one?
That restaurant seemed like a $50 tab per person would not be out of the ordinary.
Under this presumption they would only need 400 (20,000/50) customers. I would guess that there were 6 hours for the competition and 6 waiters/waitresses. 400 customers would mean just over 11 people per hour per waiter/waitress. Remember that is 11 people not 11 tables. A party of 5 would leave 6 left.