Chickens will always try to get on the highest roost. So best to have all your roosts at the same height. If one chicken doesn't like the chicken next to them on the roost even if the other chicken is several feet away, the more dominant chicken will go peck at the other chicken. So it's best to have several short roosts instead of one long roost. If your forced to have one long roost (long narrow coop) try putting up some plywood dividers to try and break up the roosts. My chickens have the balance of a drunk guy at a DWI stop. So it's best to use a wide board like a 2x4 with the wide side up. These are just my observations. My chickens are very sweet and tolerant to each other during the day, but at night if they are next to a bird they like they will peck at the chicken they don't like until that chicken moves or burrows under another chicken.