When I'm feeding a bunch of babies, there will always be one or two who won't eat unless they are covered. I feed on my bed because I have room to put out all the delis, and the hatchling racks are in my bedroom. So the covered babies go under pillows! And then I just gradually ease them out till they are more and more exposed. Some babies will eat uncovered, but really freak out and rattle and strike if they see a person moving about, so they get fed uncovered, but up out of the way where they don't see me.
The general routine for new babies, though, is- covered and slit, uncovered and slit, uncovered and not slit as a test to make sure they will just eat, then back to prey always slit until they are on adults. So they are assumed to be "good" feeders, until proven otherwise, and go straight to uncovered on their second feed, unless it took a particularly long time to take the first feeding.