How does it work? I've never been in a band nor have I really jammed out with anybody. Does the banjo harmonize with, lets say, a lead guitar? Not even necessarily harmonize, but if a guitar plays a I-V-vi-IV in the key of E, would the banjo player play the same chord progression in the key of G?
I've researched a bit and from what I can infer, most "older" songs don't take chord tones and non-chord tones into account, it looks random. (Speaking of tbluegrass, but I didn't check to see if it applied with the other instruments)