I have used this method before in a captive space like you mention. I had a smaller portable cage I put the new chickens in that went inside the larger pen. This method really did help.
I'm getting back into hatching and raising birds. I went to my storage building at the place I am moving from to get everything out and found that someone had broken in and stolen almost everything, including my incubators. :th I am now looking to purchase a new one to get started again...
I have raised chickens, turkeys, and ducks in the past, close to 200 at one time. I ended up selling out and moving for a while, but I’m excited to be moving back to an area where I am able to start hatching and raising birds again.