As long as I teach it right the first time I shouldn't have to repeat the same lesson several times over.
Are you SERIOUS? Do you understand conditioning? It takes hundreds to thousands of repetitions to train an animal. You can't teach something ONCE (or even two to three times) and expect it to be learned behavior.
For letting the be a horse... as long as horses are exposed to other horses most of them know how to "be a horse". Its programed into their DNA. I understand some people do things like not turning them out, that can lead to issues. The longer you wait to teach a horse the harder its going to be, just take imprinting for example. Horses have a learning curve, just like everything else. Its ideal to stimulate them early on.
I was thinking to myself the other day, what if I decided to waited till he was 3 to do anything. That would be a total night mare. He would be over stimulated and wouldnt really understand as fast as a horse who was worked with early on. It like kids going to preschool then kindergarden, compared to kids just going to kindergarden. The horses who had a significan amount of ground training (in moderation) before being ridden did alot better then those who just sat in a pasture (from my personal experience.)