Look like a good natural trimming , but barley half enough for shoeing , that's probley why she through a shoe . Also the back of the frog was blocked over ,good rock holder !
It's a chronic crack and is unlikely to ever go away. The shoes and regular trimming do help stabilize it so it doesn't separate more. You could put some kind of material in the crack but it would just be cosmetic. Good question.
Why in these videos do you never see the heel nail being used, there's a lot of shoe between the last nail to the heel of shoe, very easy to pull off shoe??
It is improper to use nails behind the widest part of the foot. Everything in the front half is attached to the bone. Everything behind the widest part flex’s and moves as the foot is loaded and unloaded. Nails in the rear part would interfere with the natural function of the foot. It’s also easier to quick one with a nail back there. Rarely do the heel nails on machine made shoes work out where they can be used.