According to jazz theory, improvisation is an essential component of the jazz performance, and the Two Chord is a common chord used in jazz harmony. It is often used in harmonic progressions, but its function can vary depending on the context of the music. As a result, jazz improvisers may approach the Two Chord differently when soloing over fast changes, depending on the musical context and their individual style.
One approach that some jazz improvisers use when soloing over fast changes is to focus on the underlying chord progression rather than individual chords. They may use scales or arpeggios that fit the overall harmonic context of the music rather than focusing on individual chords like the Two Chord. This approach allows the improviser to create a cohesive and logical solo that fits the overall harmonic structure of the music.
However, some jazz improvisers may choose to focus specifically on the Two Chord when soloing over fast changes. They may use chord tones or tensions that are specific to the Two Chord to create tension and release within their solo. This approach can be effective in creating a sense of tension and resolution within the music.
In the end, the approach that a jazz improviser takes when soloing over fast changes depends on their individual style and the musical context in which they are performing. Some improvisers may choose to focus on the underlying chord progression, while others may specifically target individual chords like the Two Chord. Ultimately, the key to successful improvisation in jazz is to listen to and interact with the other musicians in the ensemble, while also bringing one's own unique voice to the music.
As for sources on this topic, a few recommended books on jazz improvisation are "The Jazz Theory Book" by Mark Levine, "Jazz Improvisation: A Comprehensive Method for All Musicians" by David Baker, and "Patterns for Jazz" by Jerry Coker. These books offer in-depth discussions of jazz theory and improvisation techniques that can be useful for both novice and experienced jazz musicians.