Roosters like men have favorite girl friends so I guess the homely hens are lonely on Saturday nights. Whether a hen is serviced by a rooster or not has no bearing on when or if she starts sitting, and sitting is no indication that she has been inseminated by a rooster.
If you want to sell hatching eggs and have repeat customers, 4 or 5 young, healthy, vigorous, same age, and romantically inclined roosters for every 20 or 25 hens is the hatching egg industry average. Too many roosters is as bad or worse than too few roosters. That said I once yard bred 40 something related by blood game hens to just one rooster (four years old no less) and got an 80% plus hatch rate. Of course any hen had to be laying in order for her to have a chance of laying a fertile egg and some hens weren't laying yet. Those hens who didn't lay automatically removed themselves from being included in the fertile egg percent category.
If you keep your rooster in a separate pen and put the same 4 - 6 hens in with him say every other day, your fertility rate should be fine. After being serviced a hen should lay fertile eggs for at least 5 days without calling on a rooster.