I started out typing this but seemed to have lost my way in finding what I wanted to say is this... Have you ever tried to understand why does this or that phrase sounds good over this or that particular chord. And in most cases I try to figure out why it just sounds like it fits with this particular scale or phrase and then most times I find myself over anaylsing and always end up confused and baffled lol! For instance, I had this phrase (in the key of Db) that went:
E----------------4
B-----6-7-6----/-6
G-6-8------6-8-/-5
D----------------6
A----------------4
E
And for me anaylsing this phrase... Notes from the phrase goes from: Db Eb F Gb F Db to Eb thats how the phrase looks like with an Dbmaj7 played at the end and again this goes with me over analysing things calling this phrase is made up of the Eb Dorian scale the thing is I didnt start on the note Eb I wound up ending the phrase on Eb which gave it that Dorian feel to it. But what I do want to know is that the Dbmaj7 is made up R-3-5-7. So in the key of Db that gives us Db F Ab C.
And when I look at the phrase and compare it to the chord they only share two notes Db and F. Am I missing something here? I also notice that Eb note in the key of Db is the nineth when counting the scale degrees that is also another thing one might consider. End the end I guess we'll never have some type of formula explaining to us why this or that phrase sounds good over this or that particular chord!