Evolution of the Jazz Blues Form - Page 3
by Kerry Galloway
The use of "back cycling" becomes common. In a nutshell, it means "well, we know we have to end up HERE (say at the F chord in bar 5) so we can work bacwards and put THESE changes in bar 4".
Check out the back cycling in bars 4 and 8. These are "II-V-I" progressions that give a very strong harmonic indication of where you are going in bars 5 and 9.
By this point, it's getting harder to just use a "blues scale" to get throught the progression. Some knowledge of harmony starts to become necessary to play over the changes without playing notes that clash with the harmonie