I'm a big time horse person. I've ridden in many diciplines, including hunters, jumpers, dressage, equitation, and limited western. Cuz it's fun to jump big. I think the highest I've ever jumped on a horse is around five feet three inches. Not that the height matters as much as how well you ride, but it's just fun.
Dressage is all about details.
But you have to decide which details are important at any given moment. For example, you can't expect as much out of a young or inexperienced horse. First, you pay people to let you ride their horses. Then, finally, people pay you to ride their horses. I'm entering stage three now.