Amen to this. I’m barely 5’3”, and most of my horses have been under 16 hands - they have had plenty of ability and jump and step! My two mares (mother and daughter) are 15’3” and barely 15’2” respectively. The 15’2” hand mare I had in high school did hunters at 3’6” and Training level eventing, and had plenty of scope. Smaller horses are easier on themselves, easier to groom, mount, find clothes for, ride effectively, and they tend to have better balance.
I am an eventer so “getting the ideal number of strides in a line” is not essential to success - but ideally, a horse should be able to make the requisite strides in a line, though in the case of bending lines or rollback turns it doesn’t matter.
I know that in hunters, it is a criminal offense to do the add, but I don’t do hunters anymore.
My younger mare is extremely long (back and neck - basically a 16+ hand horse with short legs!), and she covers a ton of ground, always makes the time, and runs short in one and two stride in and outs/combinations. I am constantly setting up tight gymnastics for her to get her to compress herself and not stretch out too much in the air!
There is a trend – especially in hunters! – to prefer huge horses who can “walk the lines“, but honestly? shorter riders are going to struggle to ride as effectively on a horse that they are perched up on top of, and will look less balanced and appropriate. I had a TB who I bought as a weanling, he grew huge; very long-backed very long-necked, a tank - very wide - 1400 pounds! and every bit of 16’2”. I looked silly on him, had to do an exaggerated release in the air, my leg barely came down to mid barrel, and I struggled to get him underneath me and in front of my leg.
If you are only doing it because that’s “what you think wins“? (and are preferring huge horses for that reason), the slightly smaller but talented horses with plenty of scope and step are going begging - and they are way more bang for your buck.
One of my students (who I’m teaching basic dressage to, and tuning up over fences) is a former hunter rider; shorter than I am, with shorter legs – and her first horse was 17’1” and long. She had little control over him, was intimidated by him, could not get her leg on him effectively (or steer well), and when she had to euthanize him, started looking at horses and despite my recommendations, picked another big one - though not as big at 16’2”.
She “likes” the big ones, but I think that’s her hunter background. Her leg barely comes halfway down his barrel, though at least he is more short coupled than her last horse!
OK, off my soapbox– but I really think that smaller horses get a bad rap. They’re often more athletic, and if you can find one that jumps well and makes the strides and is “size appropriate”, rejecting them out of hand based only on their size is missing out. Just my humble opinion.