Something can be said for both methods. Personally, I use two food
bowls -- one remains the same and one rotates. My standard is
Sun Seed's Fabulous Fruit parrot food. The ingredients are:

Dehydrated banana, dehydrated pineapple, dehydrated papaya,
raisins, dehydrated coconut, peanuts, dehydrated peas, dehydrated
carrots, red pepper, orange extract, sugar.

This is a very good diet because their are no artificial flavors,
colors, or preservatives, all of which are not good for a glider's
constitution. Although they won't eat the banannas, they love
everything else in the mix. I also add IAMs cat food to this mix
(they love the lamb & rice flavor).