This is the main problem. Especially when you hear the “in every key” thing. This isn’t piano. On a guitar tere’s no difference between G and Ab.
There is a simple reason most people can improvise fine on keyboard instruments, commensurate with their interest and effort in doing so. While on guitar you still have tons of very experienced players who think “playing through the changes” is some kind of magic act, and yet can’t articulate why.
Making matters worse is that any discussion of improvisation tends to go off the rails with philsophical discussions about creativity and how it’s supposed to work, playing “the sound you hear in your mind”, and so on. This is not helping people whose primary issue, whether or not they even know it, is the mechanical one.
Yes, exactly. However the key is, it’s not that unique. I’m convinced at this point that what I have outlined here is what most great improvisers actually do, whether or not they describe it that way. You can watch our Olli Soikkeli interview where I specifically try to draw this out of him, and eventually he starts talking about “positions” which I’m certain he means chord shapes. So he either doesn’t think about this consciously, or, he might even think it’s obvious to outsiders when it’s not.
One really nice exception is bluegrass. It is very clear to me that most bluegrass improvisers do in fact think about linking phrases to chord shapes, because there are tons of YT clips on this very topic. It is super common for bluegrass players to talk about playing “in G position”, or “in C Position” — by which they mean, licks that fit under an open G chord or open C chord. They also mean this to be true even when the player is capoed up. The licks travel with the chord shape.
Here’s one such video from Zeb Synder:
I think this is just more obvious in bluegrass because so many songs are either in G or C, and they learn so many stock phrases that fit those two chord shapes specifically. Jazz is basically the same thing, just lots of more chords, and covering the fretboard. So if you like, you can think of bluegrass improvisation as the intro version of this concept. and jazz as the next level of it since it’s not linked so much to open strings.