No, it should never be necessary with a Rock. I think the lack of fertility in some of that coop was a combination of the cold, wet weather coupled with Atlas's sore leg as well as it being the two youngest girls. He's very gentle with the younger gals, not insistent at all. I've never once seen him breed Tessa or Lizzie, though Tessa follows him around like a lovesick puppy. I'm sure he is doing it by now, but I just haven't caught him at it.
 
I broke a few for breakfast that I had rotated out and Wynette's and a couple others showed the bullseye so I guess fertility is going up now.