We didn't ever spend money on extra food, except DH's alcoholic drinks when he had one.
The way we did it was (family of four): DH would use one CS credit and get breakfast (pancakes/eggs, or whatever at the food court). I would get doughnuts or something with a snack credit in the gift shop.
Then, for lunch we would share the remaining three CS credits for lunch (or even two), which was plenty of food.
Both times we were on the plan, we always had counter service and snack credits left over on the last day. But we always used exactly four TS credits per day.
It works out great! However now you have to pay for the tip and an app if you want it...