I'm definately not getting anywhere near perfection before moving on - I find I get stuck too easily if I do that.

Working through Rock 1, this seems to be working for me:

1) take an initial pass through the whole course, trying my best to play along but not worrying when I mess it up

2) revisit all the "performance" sections in turn, spending a while on each - until I get to just about passable OR feel completely stuck

3) move on to something else

4) go back to the previous thing (2) and try again - often I'll find I play it much better at this point having has a couple of days break - this seems to work quite often even when I've been completely stuck

5) revist each periodically, casually playing along, gradually increasing time between revisiting

Hope that helps!