Certain introductions to jazz teach that one should think harmonically in terms of "chord-scales" - for instance, that "E-mixed-third-7b913" and "E octatonic starting on a half step" are equivalent in their usage. This is different from classical texts, where at any given point you have to keep track of both the prevailing scale and the prevailing chord. How do I know precisely when to use one approach and when to use another? Can the chords-and-scales-as-equivalent approach describe the idea of harmonic function as well as the two-structures approach? Can the two-structures approach handle chromaticism as well as the chord-scale-equivalence approach?