Are management courses useless?
I won't comment on whether management courses are useless. But the way you approached them certainly made them so. Learning by rote the day before the exam and forgetting everything afterwards is a complete waste of time, unless your one and only goal is to get a degree at the end. If that's your only objective, then any course you take at the university is useless, really. If your objectives include learning, though, then you did a pretty poor job at it, and that's mostly on you. Yes, a bad course does not help. But there are plenty of things you could have done to make use of the lost time. Interact with students, ask the professor for more reading material, look for it yourself...