20

Average amount of tables about 60
Average dining time for lunch is about 35-55 minutes and for dinner about 50-over an hour

i would say about 20

TGI Fridays where I work has about 52 tables, not including the bar. We only use about 40 of them during lunch time. I am not sure if I understand your question completely but usually people during the week eat faster at lunch because they have to get back to work. For dinner people tend to take their time. Hopefully, I helped a little.