We are all offering suggestions based on experiences and on our own growing pains. You can tell my experience by reading about my coop. In the end just take the suggestions you feel will work for you. We all just try to be helpful to others in the nicest possible way. We've all had unique experiences and each backyard bird will present her own personality, likes and dislikes once she is home in her own space.
That being said, chickens haven't read the book. At least mine have not. I made my roosts according to the "proper" dimensions but my hens all crowd together on one roost even in the heat of the summer. They all lay in one nest box especially when the cochin is broody. My floor is 4x4 feet and the 6 full size hens have no crowding issues. I don't know if this is because the feeders and waterer are suspended off the floor giving the hens all of the space, or if they just have not been educated enough to demand their full share.
I did read about the concern for the weight of the lift-up run roof. I split my lift-up roof on the first coop/run into three sections. The ability to open one at a time kept my pullets from flying out of a larger opening. Once when I had 2 spaces open at the same time they just flew out and over to the neighbor's fence! "Cute trick," I told them.