I was playing multiplayer with a friend, and even after fully upgrading the restaurant and having plenty of seats available, we only had up to 4 customers at the same time (two groups of two) during a single day.
Even with the setting “Customer traffic to serve: Most,” this doesn’t really feel busy. It feels a bit strange. We have a lot of equipment, and I’d love to actually use it to its full potential—like cooking large amounts of meat in one oven or boiling lots of vegetables in a single pot.