How things work..
eletons use a push.
You enter a singal it's not the eleton that you just pushed into the cable traveling down the line and exiting. It the last eleton getting pushed out of the cable.
So a 3' cable would be faster then a 6' cable and that's why attenuation happens in really long cables the new eleton can't push all the other ones forward.
Now really costly cable can use a easier medum for eletons to pass form one atom to the next but normally there is no way to tell by human. I'm talking about 1x(-10^6) seconds.