http://www.guitarplayerworld.com/Guitar_Scales_Mastery_Review.html

The primary benefit of such type of course is the scheduling and that is customized to suit the student as opposed to following with the strict guidelines from the school. It does not matter when you're on holidays or the moment is late in the night time, you can always practice your own convenience.

The lessons is taken at a slow pace advancing only when the previous techniques have been completely mastered. Lesson review is also a simple process of going back and reviewing prefer to provided. Repetition does not really cost anything.