You build a separate pen and coop to raise/finish the roosters. It just needs to be our of sight and away from the hens and those roosters can't come in contact with the hens while they're in that pen, even through a fence, nor can they come in contact with the hens as a group in a free range environment. Absent of hens, the roosters establish their own flock pecking order and while you may have an occasional skirmish, it's not that bad, especially if all the roosters are the same age and grew up together. It's not as common now, but some people raise large numbers of roosters separately from hens, for meat, for hackles, or to get a group of them to about 20 weeks so you have a lot of choices to select the best rooster/s to keep for breeding. For breeding, you can pull a rooster from the rooster pen and put him in a breeding pen with the right hens, gather those eggs for a week and return him back to the bachelor pad and return the hens back to the main flock of hens and repeat with the next breed. No waiting 3 weeks, no bare saddles, no rooster drama. Doing it this way allows people to keep and breed more pure breeds with a smaller number of pure birds and without having crazy chicken math or massive numbers of pens and coops to house each breed separately. If you're planning on eating the roosters, it obviously also helps that they're separated so you can modify their diet accordingly without changing the feed for your laying flock.
