I thought that "chord track" was a nice idea. But the first track(s) that go into my project are "guide tracks." The melody pieces, in a number of "takes" until I finally get them right, and basic block chords. The guide tracks are then muted, but they remain.
Some of the guide tracks serve as "storage areas" from which I can copy-and-paste notes that will be placed into the right spot in the song's "real" instrument tracks. (It's handy to change the color of a region to indicate that you have used it somewhere.) If I'm feeling my way to see where a song will go, the guide tracks contain a lot of muted fooling-around, in no particular order. (I've even gone back and fetched something to use in a completely different song.)
The premise of what you're doing is exactly what the Apple Loops (Green/Blue) library is all about.
Create riffs and then add them in the current song you're working on, or as you do, even put them in other future songs.
Chord Track went one step further in that you could change the original chord in your riff to a new chord.
As I mentioned before , for exotic chords and trying to apply that to an audio (blue file), it would just seem impossible to do, but for a midi (green file), that would be possible as you see in the above video.