I am certain many folks will have different ways of doing it.....
If I am lucky enough to have a hen decide to set................I put her and her eggs in a large dog kennel and, of course, made certain she got out a few times a day.
The last time I did not protect one.the squirrles stole her eggs and the other hens continued to lay in her nest.
Ended up with 21 eggs in her nest.
they sat right on top of her to lay. She ended up with one chick.........enough to make her happy
I kept her and her chick seperated in a cage about 2x4.the others could see her but not bother the chick.
I intagrated them at about three weeks for the chick.
No one has bothered the chick but have read others who had hens that would kill chicks.
Thats what works for me...........I free range during the day, they might be territorial if they are in a run.