People talk about whether the arts or the sciences are harder (as subjects studied in uni), but I think the fine arts, particularly the performing arts, are hardest. Fine arts majors have to study academic subjects, AND rehearse for performances. You can bullshit an essay, you can even bullshit a lab writeup with a bit of research and ingenuity, but you can't bullshit a performance. If you haven't studied for an exam you can usually still squeeze out a passing grade with some logic and ingenuity, but you can't fake a performance you haven't rehearsed for.

I took everything in high school - english, maths, sciences, languages, social sciences, and music - and it was music that required the most effort and the most consistent effort on my part. I could usually do okay on a physics test by quickly memorizing the key formulae on someone else's study sheet in the last 10 minutes of lunch time, I could usually do okay on a French test by conjugating the verbs like similar verbs and going with the "it sounds right" rule for prepositions, but I simply could not get through a performance test in music without spending at least half an hour a day working on the sixteen notes and the tricky part and training myself not to have to breathe for twelve bars.