I have crossed my billets in the past, and want to try it on my current horse. I can't remember whether you cross the front over back, or back over front. I am thinking it makes more sense to attach the front one with the rear one over top of it. Also, there are many theories about where to place the saddle. Some say right behind the scapula and some say 2" behind it. Anytime I've ever placed the saddle farther back I feel like I am sitting too far back and not over the horse's center of balance. Like I'm sitting on a part of the back that has movement thus interfering with it. I'd be interested in your theories and experiences.
I just had a saddle fitter out to check the fit and add some wool to my Albion. She says, for dressage, to place the point of the tree a couple of inches behind the scapula. When the scapula rotates back, it needs a place to go so as not to interfere with the range of motion of the shoulder.
I think for jumping saddles that it is alright to place just behind the scapula, because the rider needs for his center of gravity to be over the horse's withers, which is his center of gravity.
Kate said that she has seen saddle placement as far forward as on top of the withers.
When I was growning up, we placed our saddles too far forward, because we did not have saddle fitters way back then.
As far as crossing the billets, I will be interested in the answers. I have not heard of doing this. What is the reasoning behind doing it?