I am seeing more than one possible definition for overfeeding here.
One person might mean feeding the fish extra food during a session in quantities above and beyond a normal portion, but the fish are eating it all. They're just bloated with food.
Another person means feeding many meals in a day that would be in excess caloric load yet not bloat the fish at each feeding.
Even another person uses the term to mean that some food is left uneaten.
Be sure to include your definition of 'overfeeding' when you say it. Otherwise we're all on different pages.
My idea of overfeeding would be either too much at once or too much overall. Leaving food in the tank (unless it's a veggie tied to a weight or something) is not my idea of overfeeding, it's just bad animal care. Since the fish didn't eat the food leftover, it wasn't fed. So the extra food isn't from overfeeding, it's from...undereating?
I have had many different fish live for 12+ years routinely over the years and I feed once per day.
Once per day is often the recommended amount for mature fish, depending on species. Even if it's a heavy meal it's hard to exceed the caloric needs of a fish in one meal if the food is of good quality. Then you've got your mollies and small plecos that should probably be fed a minimum of twice a day but that's a veggie tale.
IMO, powerfeeding is actually acting more like mother nature in summer. Lots of nutrition often and extra water flow for many bodies of water. Water changes keep toxins down the way an algae-loaded shore does and the fish are free to grow as genetics have dictated. What most of us do (once or twice a week water changes) is not quite up to par for creating the absolute amazing creature that it was programmed to become, but still adequate for long life and good size. IMO.
