I read this rule in old poultry books but have never seen it in newer ones:
“A chicken chicken coop needs to be big enough to walk around in, or small enough that you can reach into any part of it from outside.”
Coops that are somewhere in the middle — too small to walk in, too big to reach across — are nothing but trouble. Chickens need good care, and (let’s face it) we give better care when it’s convenient to do so.
In addition, coops that are hard to service usually provide limited visibility. Is that waterer in the back really working? Hard to tell. Is that an egg in the shadows? Everything works better if you can get up close and personal.