If I’m honest, it’s not how often they’re fed but how much they’re fed in terms of nutrients.
Put it this way, I have 12 fish, many of those are said to need feeding 2-3x a day. I only feed 1x every day however here’s what I do;
First off I feed a heavily varied diet. But I also constantly replenish microfauna on a weekly basis. I also have mother sponges in my sump (yes, I use a sump for filter feeding microfauna and not just equipment) which let of offspring into the DT where my Regal Angel, TSB Tang, Magnificent Foxface, wrasses and Copperband butterfly can all graze off of. I also have smaller algae growing on my wave maker and rocks.
Most of my fish aside from my Regal Angel are now 3 years old. Yes I know this isn’t recommended for everyone however I’m just putting what I’ve experienced out there