The best way to keep your horse sound is to balance his feet!
Things to watch for.
My farrier says he just has bad feet.
My farrier does not need to measure; he says he has a good eye.
Hoof gauges only work on horses with good feet.
You would have to have a different T-square for every horse.
When your farrier says: I think a horse is balanced if you have done him a couple of times and he is not lame. And the owner is not complaining.
We will have to make a special shoe and I am the only one that can do it.
Be aware of gimmicks and quick fixes.