Many good things have been shared.
I have had 1 rooster with 1 girlfriend - they were good together.
I have had 1 rooster with 2 girlfriends - it worked well. (Then the three became bullies towards the others in the flock and I moved them to another flock.)
I have 4 roosters with a flock of 12 girls - no problems. Very little mating. The two head roo's are RIR and don't let the other two roo's ignore a "no" from a hen.
Every situation is different.
Any boy chicken is a cockerel until he is a year old. On his first birthday, he becomes a rooster! (Nope, no magic happens. No fireworks. No sudden change in appearance.) After his first birthday, he USUALLY settles down into the man he will be.
Different breeds, different temperaments. And despite the "generalities" of a breed, each bird is very different and may or may not live up to the breed's reputation.
I had read that RIR were very aggressive. I was a bit concerned when I adopted two RIR cockerels. Their previous moms said they were sweet and not aggressive at all. Going through puberty, those two boys were great! No crazy hormones, no aggression - just nice and laid back. I gave them a flock of younger girls. The boys accept no for an answer. When there was danger (I am currently dealing with hunters, a fox, hunting dogs, stray dogs, and a mountain lion in addition to the normal stuffs like hawks and black buzzards), my RIR's stood at the front of the flock, as tall as they could, and gave the warning. The girls stood behind them, as tall as they could, and sang the warning.
Getting a rooster does not mean he will sound a warning or sacrifice himself.
Adopting a rooster (which I am for) does not mean you will get the truth about his past/his behavior/his temperament. OR that his behavior/temperament will stay the same as time goes on.
And yes, roosters really do crow a good hour BEFORE first light!