By just playing the game a bit as a client in pugs I’ve come to realize the search distance calibration is not really optimal. It does for example not take rtt (round-trip time, i.e. ping or latency) into account, and rather seems to base distance on geographical distance (i.e. something completely different than Internet distance).
Recalibrating to use rtt between your client and servers instead would make a lot of sense. As it is today bad peering and similar is ignored, and some ISPs have really really bad peering.
TLDR, use rtt (i.e. ping) to measure server distance, not some other weird smuck.