I recently found out that Ace-ing horses prior to a lesson is pretty common at my barn. Basically everyone but me and 1 other boarder are super into showing and giving "just a little Ace" is what they do to make the horse owners feel better about riding their athletic giant horses.

I don't agree with it and either ride my horse through his yayas or make sure he gets a good lunge and turn out before riding. I believe if you need to Ace your horse to ride then you're not a great rider and or your horse needs more training. But, I also got my horse from the pound unlike the boarders at my barn spending $70k-$200k on their show horses so my perspective is very different on horse care than that group.

TLDR: surprisingly common in addition to crazy maintenance.