Douglass Green defines "chord succession" as a movement of chords that starts in a certain area and reaches the same area (I believe "area" means the classification as tonic, mediant, submediant, etc ... and the inversions don't matter). A movement from one area to another is defined as a "chord progression". The book proceeds analyzing what can happen harmonically inside a phrase (Chap. 2.5): the whole phrase can be just a cadence; the cadence at the end can be preceded by a single chord, the cadence can be preceded by a chord succession, by a chord progression, etc.
This is an example of a phrase with the cadence preceded by a chord succession:
This is an example of a phrase with the cadence preceded by a chord progression:
My question is: In this kind of analysis, what is the last chord to be considered? He considers the chord before the pre-dominant of the cadence when classifying the sequence as a chord succession (the sequence goes from I to I), but the last chord is elsewhere the pre-dominant of the cadence. If I were consistent shouldn't I say that the first sequence goes from I to ii6 being a progression and not a succession? Also, sometimes he pays attention to the bass instead of the roots of the chords, would this be the fundamental difference between both cases in his classification? Am I missing something?