we have 2 coops in one paddock and just let them choose.
u dont want overcrowding but u also dont want just one or two in one coop cos in the winter it will be cold. u could feel the warm in our coop this winter with them all cosied up together. if u have a fair few in one coop, ul have to muck it out more often as it can get mucky quickly.
if there isnt enough nest boxes,, ul find them laying in the wrong places, which can mean dirty/stolen eggs (thinking animals stealing em not ur neighbours...lol)