Oh God, it's getting them to STOP that's an issue! They'll keep going and going until it's probably unhealthy if you keep the females in the same tank as him. When my females are in season, breeding is as easy as putting the female with the male or vise versa, and they get their business done in under 5 minutes. I separate them, and I've had zero problems. I generally have my stud breed about 10-15 times a year, and I only have a few adult females. Every 2-3 clutches, I rebreed the females.
So yeah, if you use the method I use, I doubt any harm will come of your geckos, and I don't if there's a limit to males at all when done this way.