From the Side-by-side:

Practice for UIL Marching Band: Each entry in the UIL region contest must be accompanied by the following statement signed by the director: “The members of this marching band or any of its components did not
begin preparation of the visual curriculum for this UIL contest presentation prior to August 1. In addition, no
more than ten hours (twenty hours:2020 only) of director-supervised instructional time was devoted to visual
fundamentals between the end of the previous school term and August 1.” (EXCEPTION: Auxiliary camps,
leadership training, and preparation for special summer events such as civic parades, professional football
game appearances, and other non-competitive performances are not considered a violation of this limitation.)

Because there was a parade, it is perfectly legal. And there's no specific wording in the rules about whether or not your 10 hours is "up" once the parade happens - so theoretically a band could march a July 4 parade, and still have ten more hours of marching fundamentals before August 1.

There are MANY, MANY loopholes in the C&CR. I'm aware of most.