We have 17 chickens right now....but, we have 4-5 males. We will keep 1-2 males (we have a 10'x50' run, so very roomy IF we keep 2 males with 12-13 hens). So, I figure 1 ft per bird on the roosts, and we need 3 roost bars if we put them across the 6 foot length (opposite side of the door).
If we go with perimeter roost bars (avoiding the window and the door opening), we end up with the same amount of roost space.
I guess, I am trying to figure out best way to structure it so there is an ease of cleaning and access.
Chickens definitely don't care. My neighbor has done very nearly everything WRONG according the vast majority of posts and advice on BYC, yet has healthy and productive birds. My spouse lived in the rural south for many childhood years and thinks the coop we are building is waaaaay overkill as it is (according to their southern experience raising chickens), although does concede that chickens do need a bit more protection in the more northern climate.