I had a number of girlfriends that were waitress. Yet if I tipped them well above normal, it would be noticed by the other waitresses and I wouldn't get good service by the other waitresses.
You don't always get a choice to who will serve you. Nor are all waitresses there all the time.
The food services often has frequent schedule changes. Especially with the younger waitresses, that haven't been there a long time. They even fill in for the older waitresses.