I've heard of this concept while soloing (RE: Mark Levine's "Jazz Theory Book") but I was wondering how many of y'all old guys do this when walking. How advisable is it to do this? I mean, the point of the bassline is to define the song harmonically...but I mean, there's changes, and then there's not changes. So if your pianist is stretchin' like crazy during a solo, would you stretch along with him and go right out, or keep it grounded with the original harmony? Also, when do you play the "optional" chords (those in parenthesis)? Do you wait for the leader/soloist to start 'em off, or do you ever just take charge of the harmonic direction?