IMO it can get to a point where there are too many girls.
Look at Max's Life, I think there is now somewhere around 30 girls. As per the last update there are 72 girls with profiles, a lot don't have any scenes (yet?) .. it's far too many. With that many girls you'd need 3-4 updates just to cycle through each of them once. There are so many new girls, that the original girls are all but ignored now and new scenes are all with new girls. The only bonus with that game is it's a sandbox and there are repeatable events with all of them.
Maybe it's an extreme example but too many can ruin it. I'd hate to see the gingers, Fiona, Becca, Maddie, Mary etc ignored because of to many new girls being added. Of course though knowing Killer that wouldn't happen.