My contract says that they will feed whatever amount of hay I want, and whatever amount and type of grain I choose, 2 times daily (morning and evening). Pasture turnout is given in good weather conditions, and hay amounts are not adjusted unless the owner states that they want it that way.
We are billed by the bale, so horse owners can freely come in at night and give their horse an extra flake if they want to, without penalty (or without having to sneak around!). I have the barn owner buy my grain for me, and she just bills me for the amount (lbs) I use every month.
We weigh the hay and grain, to be more accurate. Amounts for hay and grain are written down on a sheet. Each horse has its own individual sheet that states what it should be given, and the person feeding has to mark off how much hay and grain the horse received each morning and night.
I used to board at a place that touted the fact that they fed 3 times a day. What they didn't say was that it only equaled about 10 lbs/day, if that. For a growing horse, it was hell. Now that I know what my horse is getting each day, I'd prefer to keep it that way.