As of now I have 30 hens and 3 roosters - about 5 of those are bantam hens and 1 rooster is slightly disabled and young. No issues but I do think it comes down to the temperament of the rooster. My oldest rooster Thanos is the worst rooster because he doesn't protect the flock, not a single fertilized egg when it was just him and straight up is the first in the coop when danger appears lol by my boyfriend is attached to him soooo
Now my Mottle Ancona rooster is straight up the best rooster. Not too rough with the hens and respects if they shrug him off. Leaves my bantams alone even if they're willing. Calls the girls over when he finds treats and is the last in the coop when he suspects danger. He even protects my disabled rooster from my alpha hen.
I do think it's because I raised him with a group of chicks which included bantams. If you lived in NE USA I'd give him to you as I'm not looking to add his coloring into my flock.
My disabled RIR rooster was previously super mean and thought he'd be an issue...until he picked a fight with a wall and broke his leg. It's healed and he's walking whine, just a little limp but now he's super sweet. He's very protective of my polish and silkie as they don't roost with the others and the three of them are on the floor at night.
Bottom line, it's down to temperament. But some roosters are ok with few hens without over mating them