Naively I'd assume that the improvement in time accuracy GPS clocks provide must be greater than the harmful effect on accuracy created by network latency, even

Naively I'd assume that the improvement in time accuracy GPS clocks provide must be greater than the harmful effect on accuracy created by network latency, even within data centres: you can't guarantee that a packet will arrive on time, since switches can, I believe as part of their protocol, apply a random wait to a packet. I assume there must be some special method to maintain a synchronous connection to the clock on each server over the network. Could it be as simple as some QoS rules in the switches for NTP packets?