I suppose it depends on a whole lot of things.
Size of tank
Amount of fish
Type of fish
Anything else benefiting from the food
Type of food
Skimming?
In my 10 gallon I have two false percs and a regular old HOB filter. They get feed a variety of foods and the feeding schedule changes depending on the type I give them. For instance, if I am feeding a flake I may give them small amounts more often. Meaty foods like shrimp, frozen formula 1, etc. I soak in garlic and feed a little less often. In turn they tear up the meatier food pretty good and my anemone, crabs, snails, and anything that feeds off the water column gets a bit of a feeding as well.
Not that this was a real help; just what is working for me.
Shaun Legacy