I’m not asking in any kind of sarcastic or sneering way, I’m just asking. The interest that some folk have with average speeds seems to be associated with people who don’t race, and in my racey days, no-one was ever concerned with averages, just who got there first.
As noted above, average speeds while training are dependent on route, traffic conditions, other riders and so on, and are usually highly exaggerated on the internet.
I did a sub 5 hour 100 miler as a training ride from Manchester over to Scarborough, door to door, all traffic regulations observed. I rode back the day after, but that took 6 hours. I didn’t really mean anything to me, but position in races did.