Saddle fit. Yes, how it fits the horse is critical, how it fits the rider, equally so. A poorly fitting saddle for the rider will not allow freedom of, correct or effective equitation, or consistency in position and communication. Won’t do anything positive for the horse, either, if the rider has to squirm and plant to find and stay correct.
Where you mention jumping, I am going to accept that you are a regular rider and have intentions of continuing. IF this be the case, I would consider leasing a horse. This way, you are not having to adjust for different horses. There ARE adjustable saddle brands out there and you might want to consider those as well tho even those types can adjust only so much. At this point, I would be inclined to consult a bona fide saddler for the right style, model and fit for all involved. Most are pretty savvy about brand names and how each saddle should fit a horse. If leasing is not an option, this makes it a bit tougher to utilize one saddle but again, saddle fit is a key point in successful and comfortable rides and happy horses. You might have to limit the diversity of horses that you currently ride, for now, in order to stick with a better fit. Research will become your new best friend : ) Good luck with this, proper tack, ‘specially saddles, can be a bear of an adventure but sooo worth it in the end (no pun intended ; )
Sure there's right and wrong but mostly there's just a whole lotta different.