I dust my insect every time I feed. Adult frogs get fed once a week, more if needed. Froglets and other small mouths much more frequently.

I don't use forceps at all when feeding. I do try to watch all frogs eating to make sure they are ok. Not all frogs will eat when your watching. Red-eyes and other extremely nocturnal frogs won't eat until lights out and it's a little hard to observe that. So feed and watch them, if need be you can separate them when feeding, just to make sure they are all eating.