four cubes per day in a 55g sounds like a bit much, you could probably cut back a bit without hurting the fish at all.
I generally feed morning and night. One meal is a cube or two split between a 65g, 30g and 5.5g. The second is more of a snack, usually just a few pellets. Every other day I put nori on a clip between feedings for the angels and turbo snails to munch on. One or two days a week I skip feeding the 5.5g and 30g, but I don't skip any feedings on the 65g right now because I've got a picky angel I'm trying to fatten up.