I run staggered hatches (chicks hatching every few days) & have never had a problem with chicks dying from bacteria due to being the last to hatch. I also open my bators to get chicks out. If done quickly it's usually fine. If you are worried about losing humidity, take a spray bottle of HOT water & mist the lid of the bator before closing it completely. Only open the lid as far as absolutely necessary & close it as quickly as possible. DO NOT spray the eggs directly unless they are ducks & none are pipped. It is best to wait for as many chicks to hatch as possible before moving them, but not always possible with late hatchers or staggered hatches.