I remember reading somewhere that one was better than the other, though I don't remember which or why. Can someone refresh my memory? I think it was a basis for culling...
I've read about that too. As an oldtimer's monthly culling check. During the summer months, one of the things to check and cull for was early molters. No clear reason was given for that, but my thought was that hens who are molting early in the season are less productive. That's prime egg laying season. Molting hens aren't generally laying, and since oldtimers were definitely going to be eating somebody for Sunday dinner, why not cull out a nonproductive hen...
I had a very early molter this summer. She was raising babies at the time, so wouldn't have been laying anyway. I remember walking to the broody pen one day and seeing feathers everywhere. I was sick to my stomach, imagining that some horrible predator had gotten into the pen. But no, she came out from under the coop, having completely dropped her tail. So sad looking! Now, many of my hens are molting, and they look like a raggedy mess. This one early molting hen is drop dead gorgeous, a queen among peasants, and she's giving me an egg a day. I would have never considered culling her anyway, she's one of my best broodies, so has her value to the flock as a mother, not a layer. Still, it's nice to have one that I know will be laying as long as hours of daylight will allow it.
If my entire flock had decided to molt in July, that would have been a very bad thing for egg production. I would think that early molting might be genetically based, and another reason to cull those hens. (Besides Sunday dinner.) If an oldtimer continued to allow early molting hens to exist on the homestead, bred them and hatched their eggs, eventually the flock would have more and more early molting hens in it, and production would go down and down as the years went by. I'm not sure that it's such a concern to us these days. And then again, maybe it is. I've never hatched any eggs that came from my early molter. Because she's broody, and I'm already covered up with broodies. It can be ridiculous around here at times! So in a way, she's already culled. From the breeding program, that is. Not from the flock in general.
So, those are my thoughts. They may be way off base!