Something a Bit Technical about the chord progression of "Misty"

I just noticed something about the chord progression in the first part of "Misty," the famous song by Errol Garner.
At first glance, there seems to be something arbitrary in the second two bars of the chord progression:
(1) EbM7| (2) Bbm7 Eb7| (3) AbM7| (4) Abm7 Db7| (5) EbM7 Cm7| (6) Fm7 Bb7| (7) Gm7 C7| (8) F-7 Bb7|
I've numbered the bars to make things clearer.
After declaring the key of the piece: Eb major, it abruptly modulates to Ab major, and then, just as abruptly, it returns to Eb major, where it remains to the end of the first part, except for the E natural in the C7 chord in bar 7, which puts the song in the key of  F for a moment.
Interestingly, if you sit at the piano and play these chords, moving your hand as little as possible, something fascinating emerges.
The top note of EbM7 is D natural.
The top note of Bbm7, spelled F-Ab-Bb-Db is Db, as is the top note of Eb7. This is a chromatic descent of a half tone.
The top note of AbM7, spelled Eb-G-Ab-C is C. Another chromatic descent of half a tone.
Abm7, spelled Eb-Gb-Ab-Cb gives another half step descent, repeated in the following Db7 (Db-F-Ab-Cb).
Then, in bar 5, EbM7, spelled D-Eb-G-Bb provides another half tone descent, and the top note of Cm7 is also a Bb.
In bar 6 there is a whole tone descent from Bb to Ab: C-Eb-F-Ab to B-D-F-Ab. (This whole tone exception to the half-tone descents reinforces the function of the seventh and eighth measures, which bring us back harmonically to the beginning of the piece - a turnaround).
The G minor 7 in bar 7 goes down another half step: Bb-D-F-G, repeated in the C7 (Bb-C-E-G).
Both the F-7 and the Bb7 in bar 8 can be spelled with the top note as F, and then we return to Eb with another whole tone descent, hastening us back to the beginning of the first part of the piece.
So the voice-leading of the chords goes down a a major sixth from D to F: D>Db>C>Cb>Bb>Ab>G>F
The second ending, bars 7 and 8 in the repeated first part of the piece, has the chords Eb6 Db9 | EbM7. These chords can be played: Bb-Eb-F-G, Cb-Ab-Db-Eb-F, compressing the whole tone descent from the two measures in the first ending to one, and the second measure of the second ending can finish on Eb: G-Bb-D-Eb.
If that isn't neat, what is? Errol Garner certainly knew what he was hearing.

Doing Things for the Last Time

As my 73rd birthday inexorably approaches, I think of the last time I will be doing things. But you don't have to be old to do things for the last time.
My youngest daughter just gave birth to a baby girl, her third child. Quite likely this is the last time she'll go through pregnancy and birth. But still, as the date of your last breath approaches, you are aware that you might not be doing a lot of things again.
When we got our dog, Kipper, about 9 years ago, I found myself thinking that he was probably the last dog we'd ever get. When we bought a new car 2 years ago, I figured that would be the last car we'd buy. Just now I bought a new laptop to replace the ancient, clunky one I bought a long time ago. Will I ever buy another computer? Depends who gets obsolete first.
Some of the things one does for the last time are things one wouldn't want to do again anyway, mistakes one doesn't want to repeat, or things one has gotten tired of doing. A lot of my friends are retiring from their regular jobs now. If they keep on working, it won't be under  the same circumstances. It must be a relief not to have to go back to your workplace except to visit former colleagues.
You can also do something and not know that it's for the last time. When will I ever go ice-skating again, ride a bicycle, go back to Mumbai?
It's probably a good idea to think of things you enjoyed but haven't done in a long time, and then to go out and do them, if you still can. It's an equally good idea to think of things you've never done and do them for the first time. That's advice for retired people.
You're only born once, and you only die once, but in between you do a hell of things over and over again.