Hi Joe,

Hmmm, I've never thought about tetrachords while improvising, maybe it would help me if I did. I've internalized my scales to the point where I can play them anywhere and in any key. That's not as hard as it might sound, though. If you practice anything enough it will become second nature.

To me, the key (at this point in time, anyway) is using chord tones to define the changes. Not for EVERY chord, but enough to define where the progression is going. One goal to work towards is to be able to arpeggiate every scale without thinkng about what notes you're playing. This will open up your ears, man, and make the journey even more exciting.