Apparently you've never seen some of my chickens....

The hens go for the head, and they peck HARD. They're always after the head. I've seen several combs pecked badly. I've even had hens missing fingers from their combs due to pecking order. It's chickens in a run. When they're free ranging, and are rarely ever in each other's space, there is never this problem. I've dealt with this problem countless times, with different chickens and flocks and in different runs. I've even experimented with what run has the least amount of pecking issues.