The difference may also be related to exertion.
The Road to Ruins is the A partner while the Sand & Sequoias is the B partner.
On Feugo Flats , is the C partner and there are probably 50 people are the robot.
Interesting, groups of riders will congregate at the front of the group then fly off together.
The pace partner seems to continuously spawn groups of 6-10 riders that fly off and work at a harder pace than the pace partner.
Today, while riding on Feugo Flats with the C partner, I saw the B partner coming in the opposite direction and I think I could have done a quick U turn and start riding with the B group.
I was cooling down at that point so I didn’t do but it seemed like I could.
You can see the leader beacon way off so you can U turn and let him catch up.