As a musician I have been studying & transcribing various type 1 & 2 jams for the last 3 years. The more I study, the more amazed I am.

I have found that type 2 jams can be subdivided by the various musical elements that are executed. One of the most common ones is a shift from major to minor tonality (& vice versa) via the occasional pivot chord into a completely new key or by the more common modal shift. This serves as a launchpad into the next song without having to stop & start again. Phish are masters of this. The only other musicians I've heard do this are very experienced jazzers (from my personal study at least).

Some of the more risky type 2 jams involve meter shifts & added meters during the tension building. What's interesting in this case is that Mike usually brings them into it, Fish usually gets them out of it while Trey either lags behind are goes ahead of the beat as they bring resolution to a phrase. The magical moments are when they hit it all perfectly together back on the 1. When they occasionally do this, it's seems so impossible that I wonder whether it's luck or supreme musical intuition or perhaps both.

In any case, I believe they are the best improvisors in contemporary Western music. Given there is a vast library of live recordings, I think they will be studied in the future just like some of the greats of yesterday.