Memory training can happen if the CPU detects that current timings don't work at boot. Since GP never shuts down, it's possible that his memory is always hot and performs better on a reboot (when setting new timings) than after a cold boot (this is basically always true since ram chips like to be hot but especially relevant here). If GP is using XMP or has custom timings, I'd suggest easing off on them especially considering the novelty of DDR5.