Ok, Iāll bite then. The horseās natural biomechanics in some ways dictates how easy a particular movement will be for them. In training, we want to use the easy work to help them gain confidence and build strength so we can improve the movements they arenāt naturally proficient in. The āif you go long and low you are creating swing/suppleness/relaxationā mantra is the BS fundamental to that Art2Ride stuff.
Take two of mine, both completely different horses:
Case 1: Small HUS bred QH mare. Long back, slightly downhill, straight behind, huge shoulder. She naturally goes with flat knees, tight topline, and short strides behind, because thatās how her body is built to go. Of course, thatās not desirable for dressage, so the end goal is to bring the shoulders up and create a better longitudinal balance. To start to build the strength required to come up (which is a lot for her, sheās seriously built like a Dachshund) I ride her really forward and ādownā into the bridle. Her free walk and stretchy trot/canter are amazing, because her body naturally puts her poll in line with her withers.
I was going to say that this is a horse that supports your argument, but now Iām not sure I agree with that. We do a ton of small circles to bring the weight behind and then add in some lengthenings out of the circle to make the point. Even here, I need to use the ācollectionā on a small circle to bring the weight behind, and THEN add forward. Otherwise Iām pushing a downhill horse further onto the forehand. But we ride forward forward forward all the time. Haunches in on the straight lines and circles are great to get her to come up in front, but itās extremely hard for her. In the end, she does all the third level work, but only showed to 2nd because her changes and mediums didnāt have the quality to show.
Case 2: Upright PRE mare. Meatball body, short back, upright shoulder. Her natural movement is very up and down, much different from my QH flat and forward. The collected work for the PRE is very easy because the way she is built makes it easier for her to shift weight behind. She piaffed before she ever took a step of lengthened trot. Sheās not fighting her big shoulders and the long back to bring the shoulders up, but riding her forward forward forward like my QH makes her quick and tense, so I have to think about making her gaits slower and longer. Sheās also Queen of Lateral work. Hereās where things change: with my QH mare, the lateral work (Iāll use leg yield here) is used to shorten the length of the frame, bring the hind leg under further, and help lift the shoulder. With my PRE mare, who is built so uphill, the leg yield is used to break up the up-down of her gait and help her come down and relax the topline. Lengthening the frame is an exercise in itself for the PRE mare. At the stretchy trot she curls and snatches. The lengthenings/mediums are hard for her because she doesnāt have all that space under her body to come into, so to train the lengthenings for her, I use collected trot, almost passage, to build the energy and make her really sit behind and then give to release a big trot for a few strides.
TLDR, the difference is that with my QH, the goal is to bring the shoulders and the base of the neck up, but with the PRE, the goal is to bring the entire neck down and forward and open the throatlatch. One is the spaghetti and one is the meatballs. The exercises are beneficial for both, but for completely different reasons, and now that Iāve thought about it, in neither horse do I train the lengthenings first.