I feed my fish daily with food specific to each type of feeder, algae,mid,bottom,etc. If I notice any left over food I skip a day & feed the following day instead. Live food or extras like greens I feed about two or three times a week.
When I go on holiday for a week to ten days I have my helper feed sparingly every other day so that the water does not get pollouted so quickly & need a water change while I am away. I have tried holiday feeder blocks but as I have to have cat & dog carers coming in daily anyway it seemed a waste.