[Suggestion]
Not sure if you're even reading my comments, mdqp, but here's my suggestion anyway;
A global progression file used for the gallery, so that no matter what save you're playing, you can veiw all the art, even if your current save hasn't seen the scene for it. I'm pretty sure it's possible to lock a given playthrough out of various scenes that unlock images, and if I lose a save file through corruption or it getting deleted, having the gallery still having those images will make it less of a grind to play through, and make it so you don't have to do everything in a single playthrough to fill the gallery; thereby increasing replayability.