How does any saddle actually fit, any horse, ever?
Horses backs are totally different shapes not only depending on whether they are standing or moving, but also different shapes between walk and trot and canter, collected and extended medium gaits, they are different shapes on a straight line or a curved line or spiral etc etc.
Also, I notice horses toplines change day to day and week to week, depending on all sorts of things - work, the weather, trimming, bodywork, if they got a good sleep last night, how their friend is doing etc etc.
Sometimes these changes are small, but sometimes they are very, very big!
I'm not totally uneducated on this - I've done a few saddle fitting courses aimed at owners, I've read books, I've spent a lot of time thinking about it.
But I just can't understand how saddles actually ever fit horses.
Update: Alright, I've now spoken to a vet, a bodyworker and a saddlefitter about this and the consensus is that "they don't". And it's about harm minimization rather than perfect fit. No saddle was ever put on a horse that made that horse go better, we just aim for not making them go worse.