Some songs have so many chords that change so fast that it’s very hard to improvise over them. You find yourself just running after the chords and after the form of the songs. Maybe you can follow the form and you can play the “right” notes over each chord, but then you lack creativity in your improvisation because you are concentrating so hard on playing the “right” notes that you forget about being musical…
In such situations, it’s very helpful to simplify the chord progression. It allows you to improvise over less chords, making the changes slower, and gives you more space to focus on your musicality.
I will demonstrate how to simplify the chord progressions over two of the most common chord progressions: II-V-I and I-VI-II-V, as in Django Reinhardt’s composition Swing 42.
Two main functions for chords:
There are two main functions for chords that you need to be aware of:
– The unstable chords that lead to other chords (usually Dom7 chords).
– The stable chords (usually tonic chords).
Simplifying the II-V-I progression:
In the II-V-I progression – you can always disregard the II chord and improvise only on the V7 chord. That is because the V7 is the important chord. It leads to the I.
The II is neither a leading chord nor the stable chord. It is merely an extension of the V7 chord and thus less important. You can ignore it when you improvise.

Simplifying the I-VI-II-V progression:

You can hear the I-VI-II-V progression in a few ways. One of the ways is to see it just as a turnaround that starts with the 1^st degree and leads back to it. So we can make this progression very simple in our improvisation and we can think only of the 1^st degree!

We can also think of the Dom7 chord because it leads us back to the tonic. It would look like this:

Practice these two options and get used to hearing the difference between the sound of the tonic and the sound of the Dom7 over the I-VI-II-V progression.

The II-V inside the I-VI-II-V

Another way to look at the I-VI-II-V progression, is seeing it chord by chord:

C: The 1^st degree.

Am7: The 6th degree – an extension of the 1^st Degree. It shares most of its notes with C:

C chord: C E G

Am7 chord: A C E G

G7: The 5^th degree – a Dom7 chord that leads us to the 1^st degree.

Dm7: The 2^nd degree – an extension of the 5^th degree.

So we can ignore the VI degree as it is not an important chord. It does not lead us to another chord and it is not a target chord. It’s just an extension of the 1^st degree.

And we can ignore the Dm7 chord for the same reason:

The minor II-V7:

Later on in Swing 42, after the I-VI-II-V progression that repeats twice, we have another II-V7 progression:

Em7b5 – A7

This is a minor II-V. You can recognize it by the half-diminished 2^nd degree. But it doesn’t make any difference to us, we can still omit the II degree and improvise only over A7.

So the next part looks like this:

What to play over each chord:

Simplifying the chord progression allows you to play whatever you like over each of the simplified chords.

You can choose to play arpeggios, scales, licks, or other phrases, as long as you keep the new simplified form in mind and play whatever you like over each chord.

Swing 42:

Here is a suggestion for the complete A part of Swing 42 – simplified vs. original chord progression: