I'm inclined to say top teams jumped out of habit and due to a lack of understanding how the new system worked.
They got lucky this time around IF they jumped early enough, even after the race started.
At the start of the race there was an issue with the top 100 bracket. Even if you had a top 100 team in your bracket, the rewards were not properly adjusted. Instead it was showing top 5000 rewards. We had the #6 team in our bracket.
It wasn't until maybe 1 day into the race, or a few hours before 1 day that the issue was fixed.
This leads me to believe that brackets were cemented after the bug was fixed.
Had it not been for that bug, I believe that team scores would be fixed at the start of the race, and even if you jumped your entire team within 1 minuted of the race starting, the team score of the race team would be unchanged.