The diner in Ely has a 4 table rule I never heard of before

I was driving through Ely, Nevada last month and stopped at a little diner off the main road for breakfast. Only 6 booths in the whole place and one waitress working the floor. She told me they have a rule: never seat more than 4 tables at once, even if the place is full and people are waiting. She said the owner figured out years ago that if you take 6 tables at once, you mess up one order, then you spend 10 minutes fixing it, and now everybody in the room is mad at you. If you stick to 4, the wait is a little longer but every plate comes out right. She said their ticket times stay under 12 minutes even on a Sunday rush. I work at a sandwich place back home and we just take every order that walks in the door. Now I am wondering if our whole system is backwards. Has anyone worked a spot with a cap like this?