Yeah another dancer who participated in the reunion, Nikki Pantenberg (a The Velvet Rope Tour dancer who is also the singer Babyface's wife) did an interview recently as well and said that there was a one day rehearsal with Janet which was earlier in the day but the same day as the Hollywood Bowl show. But Nikki also said there was also a non-mandatory rehearsal Friday (which you can see in Jenna video talking about the experience but Nikki said Janet didn't attend because she was preparing for the tour dancer reunion dinner which was also that Friday but after the rehearsals). Nikki said most dancers showed up to the non-mandatory rehearsal and Anthony Thomas (Janet and him choreographed "Rhythm Nation" together) retaught the choreography to the dancers. So then on Sunday in the rehearsal with Janet it wouldn't be about them relearning the steps but more about going over the song multiple times for the staging of the different formations for when the different tour dancers would come on and off the stage.
I actually wasn't surprised Jenna said "Rhythm Nation" is the hardest dance she's ever had to do. Over the years many of Janet's former dancers have said that "Rhythm Nation" is one of the hardest routines they had to learn as a dancer or at the very least the hardest routine of any of Janet's songs because the choreography is so precise and intricate. Plus Janet often added more to the original choreography such as solo routines, an additional dance breakdown to the routine, and she even had a dance breakdown using nunchucks.