Ii feed mine mostly everyday. Sometimes a skip a day or two if I'm super busy. And sometimes if I'm home a lot in a day, I might feed multi times a day (flake AM and frozen PM). But it usually evens out to 5 out of 7 days they get fed.
Depends on what type and how many fish you have.
My mandarin likes/needs to be spot fed everyday, while my chromis could go a few days without it. Ive left the tank for 5 days when I was taking finals, and the fish ate the pods and whatever else is in the tank. I dont reccomend that in the long-term.
I feed pellets in the morning and frozen goo in the evening, almost everyday. Occassionally I'll just feed goo if we're out for a day, or I'll just feed pellets in a auto-feeder if I'm away for a couple days.
I usually feed a little flake as soon as I get home from work and then a little later I feed some type of frozen, Goo, formula one or two, Mysis etc. I also hang some Nori two or three times a week.
I feed my Hippo Tang, Copperband and maroon clown once during the evening everyday. The way they act at feeding time you may would think they are starved. I can't imagine skipping a day or two.
I feed about every other day mysis & brine. I feed a small amount of flake & pellets on the days I don't feed the other foods. Hanging nori I think is important a couple to a few days a week, all my fish love it.
I have the following in my 180 gallon
Flame Hawkfish
Solorensis wrasse
Candy hogfish
False percula
2 Scooter blennies
2 Green chromis
Vlamingi unicorn tang
Six line wrasse
Royal gamma
Watchman goby