When I took my MSc. most of the subjects were things I was very familiar with already, and so most of the courses were paint by numbers.
There were exceptions that were worthwhile, but it was largely an exercise in documenting my existing knowledge. I couldn't test out of things, and most subject had compulsory exercises, so I spent a lot of time basically proving what I already knew rather than learning new stuff. It was clear to me in advance which courses I could have easily skipped, so from that perspective I would not have skipped useful knowledge.
That said, of course the problem is that to give me an actual degree the university needed to know I actually knew those things and verifying that only with tests is hard to get right.
