There is no easy answer to that question. I have about 40 full grown chickens (and a bunch of youngsters) and in that number are nine, yes, 9 roosters. They do not fight; they know the dominant roo is The Boss of the flock and I'm the boss of everybody.
Two of the roosters actually roost next to each other at night, like BFFs.
Two of the roosters actually roost next to each other at night, like BFFs.