I have trained many of my corals to open up daily. My candy canes usually balloon up after being fed. Very cool. Same for my ausi brain which balloons to a verly large size.
My white brain coral, does not open up as often.
Anyway, I started to feed my corals daily ( for years fed frozen food 2-3 times a week ) with good quality frozen food several months ago and see faster growth on many corals. I used to feed the fish and I know the corals got some. Now, I feed the corals and the fish get fed.
I even like my fire red chalice to open up and see the many mouths. Very cool.
I switch off with kinds of frozen foods. Food include copepods, phyto plankton, brine shrimp, mysis, silver slides, etc. Basically, lot's of variety. I also feed my tank twice a week with flake food.
So anyway, by spot feeding daily, most of my corals open up daily pretty quickly, once they get "trained". If that's what you call it.
PS. I have found my corals don't like krill compared to the other stuff I have.
PSS. A number of corals have started to open really big after I fed a certain food once and then they keep going. After using Rod's original formula, my candy caned blew up so big to triple it's size and actually swallowed the food, really cool.