> Does varying twist rate contribute to that uncertainty? Yes, but beyond the effect that you're saying. The distance between conductors affects speed down th

> Does varying twist rate contribute to that uncertainty? Yes, but beyond the effect that you're saying. The distance between conductors affects speed down the cable. Tighter twisting also changes the distance and the amount of dielectric around, which also varies speed of propagation. These effects can be massive; a typical cat 7 cable has a velocity factor of 80% of the speed of light, varying by a couple of percent; a cat 5e cable more is often more like 65%. If you launch a pulse into a mess of mixed wiring to find out where something is unplugged or cut, you could be off by 20% or more.