Depends on the subject entirely, I did comp science, I went to the courses so much that someone I spoke to daily who I met from the bowling club(drinking and bowling, whats not to like

) but we never really talked about courses for whatever reason, about a year later we realised we were on the same course
I passed the first year easily having never attended a single lecture, the second year I still didn't go to lectures had a slightly harder time but passed most of my modules well, though gave up uni for various other reasons.
Engineering people will tell you they study all day long every day, history guys will say they just read a few books and do smeg all else, etc, etc. Depends entirely on the subject and your recollection and how quickly an individual picks up a new idea.
This all ignores previous experience, if someone has been "into" coding since they were 10, then there is literally less for them to learn in a comp science degree, while someone who has never coded before will have more to do.
You read a book on WW2 instead of some other time when you're 15 and when you're 20 it can mean you already know a crapload about a module you do on a history course vs someone else who read all the Harry Potters instead.
How much you work ends up as a combination of, intelligence/memory/motivation/course difficulty/previous experience in the subject.