In most contemporary songs in minor keys that I analyze and try to learn from it seems that there are no real rules as to how composers choose chords and melodies from the 3 minor scales. It seems like they just cherry pick from all 3 and create melodies with the m6, M6, m7 and M7 degrees without really taking into account ascending or descending melodies. Is there any reason to look into it any further than this or is it safe to say that the 3 minor scales are in fact one minor scale with the last 6 notes being chromatic?