You will find LOADS of opinions on this, and there are many, many, variables that are factors.
Amount of LR
Maturity of the tank (EG if there are lots of pods, eatable algae, etc)
Type of fish
Water quality
Quality and type of food
Filtration
Circulation
Clean up crew
....To start!
Predators are commonly fed only a few times a week at most.
Reef fish in tanks with a lot of LR can do what they normally do - graze on rock - and can be fed supplementally once a day, or perhaps only several times a week.
Certain herbivores like tangs may need more frequent "feedings" but this is more along the lines of an algae sheet or similar.
Seahorses and certain other fish (mandarins, some anthias, etc) need frequent feedings - 3 times a day or so, IMO.
Fish Only tanks - depends on the type of fish, but often once a day is sufficient.
A critical issue is to not let the fish "fool" you into believing they are starving. They will continue to eat food far longer then they actually "need" to eat.