Superb stuff, Si.
My only observation is the inherent lack of clarity that this 'how' model provides in terms of the 'what' part of practice. A SMART objective that you set yourself is only as good as the insight you have into what it is that is worth practising. Your minor 7 arpeggio example is sound, to my mind, but I suspect a lot of people are guilty of spending thousands of hours practising things that have limited value, Often these are the things that I call 'party pieces'.
An example would be my first transcription of a Jeff Berlin tune - 'Bach' off Berlin's Pump It LP. I got the notes down and could play the thing all the way through. Had this not been pre-internet, I woudl have videoed myself and posted it as a 'Jeff Berlin bass cover' and got loads of gooey teenagers posting stuff like 'Man, you are AWESOME!!' I would have sat in my woodshed feeling good about myself and start working on Portrait of Tracy, Teen Town or the Mario Brothers theme for two handed tapping. At the time, I thought I was doing something important and useful. Thirty five years later, I can see what a waste of valuable time that was. I had no reference to key centres, no idea what the chords were, why the noites worked, would never have played the tune with anyone else in any situation whatsoever and had achieved nothing more than a rote learning exercise.
SMART objectives undoubtedly work but your [i]choice[/i] of objective needs to be properly thought out or you will be efficiently producing a useless product.
Great thread, Si.