These days I think of the pick as barely grazing the top half of a string, with glancing blows that don’t change its path. (In reality it must do more, but that’s how I think about it). Then, one can smoothly vary the angle of motion at which the pick hits the top of the string, and this lets one dial in various degrees of UX or DX (upward or downward escape). To me, now it is really naturally to think about an angle, that can be positive (UX) or negative (DX), where the switch is the transition in 2WPS. (The pick is usually oriented 90 degrees plus this angle, e.g., it is normal to that tangent path to the string.)
So rather than thinking directly about UX or DX any more, it’s more about how much angle I want. This is interesting… usually the angle might be ±20° or less, but sometimes it seems to be much more. I have noticed that the further the upcoming string jump the more extreme the angle that precedes it (possibly to get the pick high enough), but I’m not really sure yet.
I’m still not sure how to view sweeping, because it seems to turn the pick into a ramp that climbs up over the strings, and it seems alien to the concept of barely hitting the top of a string. (?)
Anyway, I’m curious if anybody has thoughts about this way of looking at things and any advice.