So, this is going to be a convoluted question, maybe... When improv-ing, I use major fourth's alot, primarily because it is convenient to hit. I could hit the third instead, but it's a bit more of a reach, so I play cleaner on the fourth. I've read around online and I see focus on other degrees: Most common: 1/root 2nd most common: 5th 3rd: Octave 4th: the third 5th: 6th or 7th then maybe the 9th? or 13th? The fourth doesn't ever seem to come up. I don't know that I ever play it emphasized, but I guess my question is... how common are fourths in your bassline and do you use them as anything other than passing notes?