I'm not a great believer in writing courses, though it must be said I've never been in one. It probably depends on what kind of writer you are. I'm very un-analytical about what I do. I don't plan much for the first draft. I try to let characters come out by themselves, rather than designing them. But other writers work differently, and for them the teaching process - which at least forces you to consider what you're doing, and why - may be very helpful. At the very least a creative writing course mandates someone to spend a period of their life just writing, which can be hard to do otherwise. But beware of thinking too much about what you do.