If you can judge it properly, 5 or 6 feedings a day would be close to ideal. The problem becomes trying to judge it properly. (5 or 6 tiny meals a day would also be better for people but none of us even try to do that many feedings that are that small.) A more common problem with many fish keepers, especially those new to the hobby, is grossly over feeding their fish, even when they only feed once a day. I feed once or twice a day depending on what I have in a particular aquarium. If I miss an occasional meal for my fish I do not worry overly much about it, just as I would not worry too much about missing a single meal for myself. The concept of skipping feeding one day a week is pretty common in on-line forums and has no relationship to reality in a well controlled feeding regime. On the other hand, if you often overfeed your fish, that day you do not feed them gives them a chance to hunt out their own food from the abundance of material on the tank bottom that has resulted from all the overfeedings. In that way it would help somewhat in controlling the rotting food on the tank bottom and would thus serve a purpose.