I was reading about Gorgonians the other day and it mentioned that food received by one polyp is shared throughout the coral. I would assume this is the case for other corals as well that are so interconnected as one entity. But saying that, I still try to feed them all, lol.
Depending on what coral your referring too. SPS polyps I don't feed each one, lps like euphyllia, blastos, micromussa get fed individually but a chalice I would not. If your meaning zoas/palys I would dust the colony.