Well theoretically, the SOL translates to about 1 ns/foot. In "real world"
terms I always allow 1.5 so 6000 miles would be about 50 ms. Now given that
the "sunk" time is about 15 ms (what the RTT is to a machine across the room)
you have about 65 ms for send-transit-bounce-transmit-receive. Now for
me to ping the last stop (5 nodes from here) before leaving Orlando is 50 ms.
The next node in Denver averages 110 ms so for Orlando - Denver you spend
about the same amount of time routing as you do travelling.
Will say that the SEA-Clark-Chicksands RTT in 1968 was measured in
whole seconds for 100 wpm TTY comm.
Considering the amount of processing you can do in a single millisecond, I
suspect that so long as the 'wall is not busy with something else, the
processing time will be lost in the noise.