This is going to sound a little weird but I'll give you a "for instance" example. Let's say I wanted to use morphs/ blend shapes to animate a convincing breast bounce jiggle. If you look at the breast up down dial 1 it's a range of influence encompassing the entire breast and a bit of the skin surrounding the breast mass. With breast up down 2 the falloff of influence is tightened to encompass more toward the center off the breast. With up down 3 it's tightened further to encompass just the nipple and surrounding flesh there. Now if you take that and a set of side to side or swing left right morphs with similar fall off ranges and you mix that all together meticulously in animation frames you can achieve a realistic undulating bounce with the effect of gravity pulling in varying degrees during motion. It's the reason for the numbering in the movement morphs, it indicates falloff or degree of force.

I have a similar set up for buttocks too lol. But that's another tale :D