When I was showing my horse, he would ALWAYS do this. Same foot everytime. The 3 others, it take a bomb to get them off. But my farrier always tried to use a few nails as possible. After we went through everything (diet, confirmation, angles, types of shoes, etc.)it just came down to he put a few more nails in the one shoe. Problem solved, LOL Never lost it again.
But now that we don't show, he's barefoot. And you can, it is a nicer way to go. JMO. I think some horses "bad" feet could be cured if they actually just got to use them