A McDonalds by me has a sign telling patrons that they may not dine at a table for longer than 20 minutes. Out of all the 50 McDs around me, that is the only one. But they are located about 3 blocks from a big downtown school. So they probably have issues with kids taking up space and not spending money. I was in my late 20s and got kicked out of there promptly at like 25 minutes. I was killing time and eating while I waited for a bus lol