Well, I can tell you what I like doing. The lessons that are play-alongs have Jam Tracks. You can take your blues stuff over the old fundamental jam tracks and make something new to reinforce your understanding of the older lessons and the newer ones with a Jam. 

I started with the blues course, and I'm in rock one now. When I finish the rock one, I'll go back to the blues one with all my new skills and understanding to reinforce both courses.