In many ways the toe defines the heel, so I don't think the heel should even be considered until the toe has received all the work it might need first.
Don't worry about the heels, do something about them. Shoe the bone. If P3 needs to be lifted behind, then lift it. Low or weak heels aren't good at supporting the weight of the horse they're under. They need to be replaced by heels that can support the horse. If P3 needs to be let down behind, then let it down. Shoe P3. The horn of the hoof wall tells a story. Listen to it. The hoof wall is not the story, but the teller. Get rid of what hinders the hoof, and utilize what helps the hoof. If you do this you are practicing farriery.
I didn't get these graphics quite the way I wanted them, but they'll do. The foot on the left is an example of the common use of wedge pads. This use of wedge pads is the reason they have received such bad press. This configuration will cause the heels to experience more stress than if just left alone.
The foot on the right is more like the foot I want to see.
Even better than wedge pads is heel reconstruction. If the money is there, heel reconstruction can do incredible things for a foot. Heel reconstruction is like crowning a tooth. A saturated fabric technique, much like fiberglass, is used to build on the existing heel. This process allows us to create the type of hoof we think will support the horse best. Reconstruction takes an otherwise deficient hoof and exerts forces on that hoof that mimic forces the hoof might have experienced had it had a more desirable shape originally. This can cause the new growth to follow the influence of the reconstruction, producing a more supportive natural hoof (with luck). Even when this doesn't happen, the reconstructed hoof can make for a sounder horse.
These drawings are all from the same base drawing. I used this drawing because it shows an ugly foot, one that can cause serious problems. I've over done the therapies a bit, but sometimes I will do it as shown when I feel I need to force the point.
