Its a good question. I currently have 308 girlpacks in my folder, and less than a third of them ever populate within the game. I can also almost guarantee that about 20 of them will show up every single time I start a new playthrough.Do girls spawn in random locations or is it possible to specify in the respective data file?
Loaded in 4 packs but either not spawning or the game can only find 1.
There certainly seems to be a preference for ones that are new and/or updated, but beyond that, I really don't know what the game looks for to pull certain ones, and why some are never included.