I think the arcade stuff is a bit grindy, not in the money department, but the scenes, like even holding shift to skip text to go where you unlocked a new thing, the animations are still normal speed, so doing them over and over and over becomes quite tiring and boring. I know I still have a few scenes left to unlock (actually I don't know how many) but the grind for minimal gains discourage me.
I don't like watching scenes in the galery since, well, it doesn't feel like it's the character doing it and rather just watching regular porn
Edit: although I do have to say, this game is impressive, if you remove the grind, there is still 15+ hours of gameplay, compared to the 20+ with the grind,