Sometimes it doesn’t matter how many hens you have,roosters will selectively pick hens to breed with more frequently then the rest,I consider those pairs.Ten to one is a good ratio,roosters are more hormonal in the mornings and late afternoons.Maybe when you lock them up,keep him out in the late afternoons,that’s what I do in spring to help the girls a bit.Are any of your birds bare yet?Barr back bothers the owners more then the hens usually,don’t worry about that stuff unless it’s clear the mating is too much and/or bird are getting injured.