It’s a good suggestion, but like @JB_Winnipeg says, I already have regarding USX. Right now I’m around 96 bpm with my left hand on a sixes etude, but only 78ish as I ascend the neck. The fingers actually move better when spread out (Scott Tenant, classical guitar guy, talks about this; he’s right), and from fret 10 or so on up the frets get a bit cramped.
My right hand trem is around 180 now, with better evenness than in the video. Not lightning speed, but good enough to play the sixes thing at my goal of 100 (Tommo recorded it at 120, but sixes at 100 is too fast for hopping, so it’s a decent goal for now). When the left is more consistent across positions, I’ll work on synch.
So you see - I do have a clue about the way forward with USX;)
It’s actually the most pleasing part of my practice, because I know where I’m trying to go and what to do (I think) to get there. But many - most, I’d say - aspects of guitar are not as cut-and-dried when it comes to improvement as single-escape is. (I said cut-and-dried, not easy. The Pickslanting Primer is hard work, but find a motion, find some speed and synch up is not exactly a process shrouded in mystery. Thanks to Troy.)
When it comes to lots of other things… That’s where the one-thing-only deal intrigues me. I’ll repeat: not because it’s repetitious, and I have some strange fascination with repetition. But because - thanks to some posts to this thread - I’m starting to see that that approach works because when you drill on a lick for hours on end, you’re forced to examine the minute details. And that may be where the progress is actually made.