I always make a point to talk to EVERYONE in an RPG (Except for Amira in MGQ Paradox). I will be sure to sleep in class at least once so I don't miss the questline you mentioned. About how long is the game in terms of hours though?
The game is a non-linear progression and has no ending. Accordingly, it is difficult to guess how long it will take to see all the content. Like for example, if you only play on a bad reputation, you will miss the dialogues of a good reputation. + just approach the NPCs and talk to them, you can also skip special dialogues when you are on your knees, as the characters comment on the fact that you are not on your feet (Mara, Genia, Ashley, itc) ** replaying the game again, before the quest with searching for documents on the football field for Genius -> I discovered that if you approach her on your knees at that moment, just before the conversation begins, she will throw chocolate cubes on the floor for us to eat, noticing ours position. Usually, if you just approach her without being on your knees, this won’t happen. This is an example of a one-time interactive that can be skipped.
Reading the thread about how to quickly farm money from players here, they either forget about some opportunities or simply haven’t found them. Since the game has no directions, no hints, no hints of interaction, you have to look for this interaction yourself, so everything depends only on you - how quickly you try everything in this game