I had the same issue and once I got the concept and was able to play albiet at a slower pace I moved on. On a few lessons I went back to revisit and found that it wasn't as daunting the second time around.

As far as the GF1 and 2. I can see me going back and revisiting some of those in the future just because some of those concepts are eye opening. Those are good assets and it's great to have them as a reference