In different routes, you would have to be mindful about saves in order to get full gallery. Being able to get all scenes in one playthrough is aimed mostly in this kind of games, so I think it's not a good idea here
Well I was thinking about using the succubus club (or something like that) so you can pay to watch scenes you missed. And even if that isn't an option I'm sure you cloud just go for a harem route or something like that.
