I do a little with mine, but the only one that gets consistent practice in my stallion. My reason is really more a technical prob. I teach lessons, so have a lot of different people working around my horses. They don't know Parelli, and I'm obviously not at a teaching level for it, so can't legally teach it to them, but can't afford to lose the income from teaching lessons. So, my stallion gets it, because I am the only one to handle him, and the others get enough to respect my space and be somewhat responsive.
"Keep a leg on each side and your mind in the middle"