When you get ready to jump a 3 foot course at a show, you’d work on 3’3 or 3’6 at home right?
In my opinion it’s the same in dressage whether for training or show. In other words, get the horse highly responsive at home with the absolute lightest pressure and cues as possible and when you are in the show ring , it’s not much different from being at home even under stressful situations.
Since being “on the bit” is an actual frame and movement achieving balance and harmony, why on earth would you use a bit if you didn’t have to? Steady support on the outside and ride inside rein to outside leg works in both a hack and a rope halter if……..and only if…….you release the horse on time. The aids (hands and leg pressure) need to be released as quick as the a snapping of a rubber band. After all, the release is what teaches the horse, not the pressure.
I’ve seen so many dressage folks ride with way too much pressure and fighting their horses through simple tasks such as turn on forehand and haunches. In reality, a loose pain free rein relaxes the horse- doesn’t “trap” the horse into a frame and when you achieve nice collection in a hack or halter……it is for real.
Bits hurt unless you ride so loosely that frankly you don’t have much difference between a bit and a bitless ride anyway.
After spending a lot of time “fixing” horses that are pissy, hollow, resistant, and just plain miserable
I’ve come to the conclusion that starting folks out in a hack or halter and training the horse to that amount of lightness is reward beyond measure. We can get collection and balance with out ever putting a metal bar in our horses mouth.