I left mine in too for the first hatch, I found it to work well, held them from being rolled around too much but still allowed some movement needed to hatch, especially the side pippers. Have tried cut down egg cartons before and found them to be too restrictive.I didn't take out the turner rack. They seem to be ok with it in. The ones that were upside down are the ones that hatched so I'm happy about that!
Will take rack out this next hatch as I have made a divider to separate crosses,
we'll see if the rolling/pinballing is an issue.

It's going to work