1st and 2nd year I went to most classes, except a few 9ams (surprisingly better about early starts in 2nd year living off-campus!) and one module which was really badly taught and the lectures were running behind my seminars anyway, so I already knew te material.
3rd year in Germany I've barely been to any lectures, because 3/4 of them are at 8.15 and I have to leave my room at 7.15 to get a ridiculously crowded bus to them. Everything's online, and that early in the morning, I can barely concentrate, plus anything that's said that isn't in the notes, I'm probably not going to understand anyway. That said, I am planning to go to most of my classes next semester, but the earliest is probably going to be at 11.45.
Next year I'm commuting, so if my timetable somehow manages to cover more than 4 days, I'm scrapping whatever's on the 5th and not bothering with it. Same for if I end up with a day having only 1 hour-long lecture. As long as I make sure I catch up on the notes another time, it's really not a problem.