I watched that video where she was doing that and it was indeed impressive! It looked like it didn’t even phase her!
I’m finding that I can do more of a wrist motion around 160-170 bpm, but for those top end speeds it is mainly all elbow. I’ve been messing with trigger grip all day, just doing moderate rest strokes. My right hand wants to string hop when doing DWPS / USX, regardless of grip / orientation it seems. That will be my secondary focus after the UWPS / DSX stuff. Seeing you do all of these motions gives me hope.