>Dave, I started out tongue blocking purely on the left side. Hell, it >wasn't untill I got Jerry Portnoy's class that I realized that players >blocked out of their right side:)
There are players that like to use the left side to play single notes (blocking and chording in with the higher notes). For the most part, the diatonic blues players tend to play single notes from the right side (blocking and chording with notes lower than the melody note). There is definitely a different sound to the two methods.
Of course you can't chord adjacent to hole 1 unless you switch to playing out of the left side. And if you chord adjacent to hole 2 playing the melody out of the right side, you'll only get one note with which to chord. Some players, therefore, often play holes 1 and 2 out of the left side.
Jerry focuses more on puckering out of holes 1-3, as a primary (but not exclusive) approach to TBing in this range of holes, swithing to TB from hole 4 and up. Kim Wilson also uses this approach, and I can hear it often in Little Walter. Jerry explores this method well. There are many TBers who TB all the time, or almost all the time.