it all depends on the individual birds in your flock, some times I'd end up with 10-12 hens and 2 roosters and they did fine. one time ended up with 21 hens and 3 roosters , and one of them thought it was funny to start crowing wars at 3 am then he'd go back to the coop, so he found a new home. the remaining new roo was to aggressive even after hormones leveled out, with the hens and went bye bye too. Now day my older rooster is scared to see new ones put in the isolation pen he was happy with 5 and now he's got 18 to deal with on his own and when hens get on one he goes and hides in the coop.