Knowing Chord-scale relationship simplify the harmonic demands of the tune.
Many chord progressions are: 1 6 2 5
I vi ii V I
Many such chord progressions utilize the same notes in their respective scales.
So when you recognize these relationships, you can reduce a multiplicity of chores to a few basic key areas.
For example: All the Things You Are
the chord progression is:
Fm7 — Bbm7 — Eb7 — AbM7 — DbM7 — Dm7 G7 CM7
these chords can be analyzed as:
- vi – ii — V — I — IV in key of Ab
- then followed by ii — V — I in key of C
It is important to hear to hear these theoretical relationships, not just understand them intellectually.