The Snaffle Bit vs The Shank Bit
The snaffle bit allows me to work my horse's head from side to side and to get him to begin to utilize his neck. With a snaffle bit, if I pick up the reins and I putt ten pounds of pressure on the rein, that's exactly what the horse feels, ten pounds of pressure. It's pound for pound. If I pull a pound here he feels a pound there. With a leverage bit, if I pull 1 pound he feels 10 pounds down there. That's a big difference. When I train my horses, I predominantly use a full cheek snaffle bit . Should you ever use a shank bit? Yes, simply because shank bits are often required in the show arena.
A leverage bit gives me the feeling of having more control than I actually have. But, in fact, the leverage (or shank) bit doesn't give me any more control than any other bit. If I have to pull 5 pounds to stop my horse on that bit, I still have to put 5 pounds on this bit. Except I'm only pulling about a pound's worth because a pound from me feels like ten down there due to the leverage created. It makes me feel like I have more control. It makes me feel like the horse is softer and more responsive, But if I allow him to, the horse will soon begin pulling on the shank bit - just as he would any snaffle bit.
A leverage bit will allow me to teach him to keep his head straight and break at the poll - but that's about all I'm going to be doing. I do use a leverage bit, if I want to work on keeping horse's head in position or to keep him square between the reins. But while the bit might be keeping his head correct, it's my body, my seat that's telling him where to go. For instance, if I were riding toward you and I tell the horse to take his hips to the left and his shoulders to the right or the left, then it's my body that's telling the horse how to move, not the bit. The bit is just keeping him "in frame."
The reason then that I don't train in a curb or leverage bit is that I can't work the horse side to side; I can't work him vertically