I feed outside of their cages, because I don't want them getting used to being fed inside of the cages. For me, it's a conditioning thing. I don't want them, mistaking my hand as a rodent, when I go to take them out of their tank. They quickly learn what the feeding bin is, when feeding time is and will associate that time, to being placed in that bin.
It's also a convenience factor. While my snake is eating, I can spot clean the tank, change out water bowls or clean the rack.
Good Luck
Wayne