Seriously, 30 years of practice, folks
Part of it is that Trainer A has a different goal and approach. This is being used primarily as cross training, not prep for future jumping competitions. It gives Theo a break from the monotony and gives us more tools to build up his strength. Our latest grid is a bounce-one stride-bounce combo. Nice and simple, fits in the indoor easily. The gotcha is that she sets it short. Most of my previous grid work was set with carefully picked distances that encouraged a natural stride. She's doing this to encourage Theo to use his back and sit to make it work.
Papi and I agree that she's a bit crazy.
Cantering in with a tight set pole, bounce, short one stride, bounce, and out, set around 2'3" right now. It's a struggle, since Theo comes out of the first bounce stretching into that open space, then realizes he has no room to fit in the stride, then there's another bounce to manage. My life flashed in front of my eyes when he blew through a half halt, got into the second bounce with too big of a jump, tried to get his hind legs on the ground before he was done with the jump he was going over, hit that jump, sort of floundered over the last, and somehow managed to get over it without his hind legs ever getting stable. I was impressed. Terrified, but impressed. He's quite coordinated at times.
After that, he decided my half halts were a good suggestion. Our last pass through the grid got what Trainer A wanted: balanced, calm, sitting and using himself instead of just plowing through. It's a very effective way to get him cantering, thinking forward, and correctly responding to the half halt instead of trying to drop to a trot. He loves to jump and he'll jazz up when we're doing something challenging.
This is his jazzed up face
I suppose I shouldn't beat myself up too much. It's not the actual jumping that's screwing us up. Going over fences is the easy part. Getting that perfect canter and keeping it through the whole thing without resistance or him locking his neck and back is the hard part.