Consistency is a great teacher (Pat Parelli)
I don't care where I start. I care where I end up (Buck Brannaman) 
It'll probably take more than once but less than a million times (Ray Hunt)

Horsemen know about the importance of repetition. Especially, if a horse is scared, it might take some time and several tries until he can manage. Sometimes it seems to take forever. In that case the wisdom of these horsemen is reassuring to me and helps me to be patient

Brannaman says in his videos that he doesn't care where he starts with a horse but where he ends up. If he has to go over an exercise again and again, he does - knowing that some time in the future the horse will get it and he can start where he ended up the last time.

Warwick Schiller compares the learning process of a horse with the one of a human. As adults we might have trouble to remember the exact dates of a specific war that we covered in history classes years ago. But the ABC is deeply ingrained in us - because we have repeated it a lot and use it daily. It's similar with horses: In order for a behavior to become a habit, it needs to be repeated a lot. And that takes time.