Pretty much, since the MC's bedroom is a "safe location" in terms of saving and keeping the save working in the future.It will only autosave while sleeping.That and leaving it on by default made the game lag quite a bit from what I heard.
Does going to H-scene or doing the girl's quest at night not autosave the game?
Technicality.It should save every time the day changes.Which usually means going to sleep.