in my honest opinion, it never hurts to spot feed any coral in your reef tank. whether it be featherduster, mushrooms (wiggly things), zoanthids, polyps, etc... some of the others corals that have mouths you could spot feed small pcs of silversides,shrimp, etc... and you will notice the difference, they seem to be happier, opening larger, and may spread quicker then you would realize. but as for feeding dusters, zoanthids,
finger leathers that use small tiny polyps to grab the food out of the water column to eat i would suggest spot feeding some type of plankton. you do need to feed them alot of it. maybe 2 - 3 times a week. my suggestion would be to either get some DTs phytoplankton or Phyto feast. i have tried the DTs. But i have heard nothing but very good things about phyto feast, and ppl i talk to on some of the forums are switching over to the phyto feast. just do a google search for phyto feast, and you will find plenty of info on the product...
i forgot to add that, if u start spot feeding the plankton turn off filters, skimmers, and powerheads for a hour or two. so the corals can filter feed. i try to get the plankton close to the corals polyps as i can so the little bit i fed will suspend around the coral. if you got cleaner shrimp,
peppermint shrimp, or other shrimp, make sure you feed them first along with your fish. since the lil buggers will steal all the plankton from the corals.