I'm with you. I think I have every course except one of the songs, BBG, and How to Read Music. I've started using my tickets to pick up the challenges. I figure I'll take advantage of the tickets as long as Griff is offering them. As soon as I own everything, then I'll just sit on them until he drops a new course, and I think I'm only a couple of tickets away from doing that.
And, yes, course overload is a real thing. Last time I was looking for something to work through, it took me an hour to make a decision. Just too many good options and things I want to learn.