How do you teach a horse to stand at the mounting block and why do Anderson and Parelli both prioritize this?

Teaching a horse to stand at the mounting block is something both Clinton Anderson and Pat Parelli prioritize for a reason that goes beyond convenience: a horse that moves away from the mounting block is a horse that is directing the mounting process rather than the rider, and that dynamic — the horse deciding when and how the rider gets on — is the foundation of multiple other problems including moving off before the rider is settled, spooking at mounting, and resistance to being caught. Clinton Anderson's mounting block protocol is built on the same principle as his gate work: the horse waits, and every time it moves away from the correct position at the mounting block, it is sent immediately to work. Anderson backs the horse, circles it, or yields its hindquarters, then asks it to stand at the mounting block again. The horse quickly learns that leaving the mounting block means work and standing at the mounting block means rest. This simple equation, applied consistently, produces a horse that walks to the mounting block and stands of its own accord within a few sessions. Anderson also teaches the specific position: the horse's barrel should be parallel to the mounting block and close enough that the rider can reach the stirrup and mount without leaning. The horse's head should be forward, not bent away from the block. A horse that stands angled or bent will move its hindquarters when the rider's weight goes into the stirrup. Pat Parelli's approach emphasizes building the horse's positive association with the mounting block through the Squeeze Game. The horse is sent back and forth past the mounting block, through the space between the block and the fence, until it is completely comfortable being in close proximity to the block from all sides. Only then is the mounting position established. Parelli's logic is that a horse that is comfortable with the block as an object will stand next to it without the concern that makes horses drift away.