I'll get yelled at by someone I'm sure, but I feel like there's diminishing returns on the quantity of girls well before you reach that magical 15 number.
Even if 5 girls are actively involved with fucking/touching/licking/etc the stunt cock at the same time throughout, that means you have to fit not only them on screen, but also somehow fit another 10 girls in a 200 degree arc horizontally around/above the camera.
I just can't see how you would physically even fit them all simultaneously on screen without requiring them to be far enough away from the camera that the visual quality it sub-par at best. VR clarity definitely suffers from getting exponentially worse the further from the camera something is.
I guess the exception would be if you were to rotate out that "group of 5 girls" every so often to work through the entire cast of 15, but I don't know.
I'd personally much rather have 2 different scenes with 7-8 girls each (or 3 scenes with 5 girls each) and be able to just focus on any of them during the course of each scene since they could each be actively involved still at that point, instead of constantly having 10 girls off to the side views who are maybe fooling around with each other or maybe just playing rock/paper/scissors but I can't really tell since they're so far away from the camera that it's fuzzy...
Edit: even just rewatching the Euro harem scene with 14 girls, there were huge portions where multiple girls were literally completely blocked from view for extended periods. Half the number of girls (7-8) but much closer to the camera and actively involved with the male I think would be a much better experience. But maybe that's just me.
