All I can think of, Joe, is that I've tried lots of different variations in speed, pressure, and patterns while stropping. Another factor is sound. We all know about "singing" razors. I've noticed, even with "non-singing" razors, there is a particular high pitched whisper, or rasp that comes from all of my razors when they are at optimum sharpness on the strop (particularly on "smooth" leather strops, not so much on a Russian).
I hope this helps,
Scott