Not knowing this existed at all was the largest and most immediate problem on my side. At various points in the past I have definitely tried doing what I thought was some kind of “no pickslanting, just moving the hand back and forth” scale playing. That’s what it looks like people like Andy and Paul Gilbert are doing, and so a lot of players probably try to cop that. Predictably, that went nowhere for me.
Instead, I kind of came at this backwards. In the attached blog post there are two examples of the same lick we filmed a couple years apart and you can see how different the motions look. So somehow, by trial and error, I was learning to dial down the arm and use more wrist. It was not intentional. As a result of our work on crosspicking I became more conscious of this, and that’s when it started clicking for scale type playing. But only very recently, like over the last, I don’t know, year or so.
So how do we teach this? I actually like the bluegrass roll patterns, as one possible approach. Because they won’t work until you match the arm position with the wrist motion of the correct flatness. Once you figure out what “flat upstroke escape” and “flat downstroke escape” feel like, not only will the roll patterns start to work, but then you can do your usual 1wps types of lines that way. Gilbert sixes, Yngwie six-note pattern - if you’re a rock type player, for example.
Of course you could go the other way - try to do the flat 1wps lines first and then connect them. But if you do them separately, then you can’t really tell if you’re doing them both from the same exact arm position - which wrist-only 2wps requires. The roll forces you to do that, because you’ve got your escaped downstrokes and upstrokes in the same phrase.
That’s one suggestion anyway!