Chickens prefer to roost when they don't have to grasp to stay on. That's why the 2x4 on the flat works so well. When grasping they must keep a more elevated posture that doesn't allow them to sit. I've noticed mine seem more relaxed and calmer on the wider roost. Less joustling for position. Also in cold climates they need to be able to sit on their feet to aid in staying warm.
I've never found community nest boxes to work very well. 3 or 4 nest boxes would be must better. Locate them so that they are lower than your roost.
I've never found community nest boxes to work very well. 3 or 4 nest boxes would be must better. Locate them so that they are lower than your roost.