Every caterer learns that the size of the spoon in self serve situations affects how much people use. I try to use a size that allows for people to serve themselves in one scoop- it speeds up the line, also.

For servers, you select the tools according to the nutrition plan and the available food for the meal.

At any restaurant supply store, you can get ice cream scoops, ladles, and spoons in specific sizes.

Theoretical size for starches is half cup, most people prefer 3/4 to 1 cup.

Standard serving for veg is 1/2 cup. I try to make sure there are 2 at any meal, esp for poor folks-

Desserts, ice cream, canned fruit. etc 1/2 cup minimum.

Soups, stews 8-10 ounces, 1- 1 1/4 cup

Meat 1/4 pound raw= at least 3 ounces cooked

Calcium rich food (milk, yogurt, cream soup, ounce cheese, etc) 1 cup every meal

gravy, 1/4 to 1/3 cup

bread 2 slices/ 2 ounces, 1 tablespoon butter or margarine

It may encourage your servers to be more consistent if you point out that there is a delayed pain of a larger portion this time is the disappointment when a future portion is "smaller". This can trigger a lot of upset feelings-