Maul was the 'secondary' villain, so he was usually down next to the stage while Vader and troopers were onstage. They replaced him with the Seventh Sister or Kylo Ren when they revamped the show in the mid 2010s. My brother got to do a show w Kylo Ren before it closed, so he was lucky enough to participate in both versions of the show.
I always did it during the summer, and they needed both the villains to accommodate all the kids participating. I wonder if they sometimes just cut the secondary character when they had fewer participants???
Either way, we were lucky souls to be able to be Jedi graduates