Well, in this case....I'd still not put rainmaker on every single day. You would be better off to let his water tank run over, because then the hoof can still breathe. Hoof sealer isn't going to help, either, like I mentioned in another thread. Plain water in super dry heat isn't going to be a problem.
Does your farrier get a good smooth roll on the walls? Since they start to crack right before he's trimmed, I'd bet a little steeper bevel would help stop that.
Now, ignore the soddy shoeing in the first pic, this was the first time I ever saw this horse. See the surface cracks (the hoof was rinsed off so we could see-it was super muddy). The next shot is about 8 weeks later,( 2 trims later) and the cracks are growing out, and the owner says he's ALWAYS had the surface cracks. Note the round wall (this hoof is still a work in progress for other issues, but illustrates the cracks). No moisturizers added, after I pulled shoes, and the roll kept the hoof from chipping between trims (this case was trimmed every 4 weeks cause he had so many issues) . I don't have more recent pics, thanks to maternity leave, but I checked on this horse a couple of weeks ago, and the cracks are almost all grown out and he's not chipping between trims as long as the bevel is strong enough. He's got thin walls like you see in most TB's, so I used him as an example [/img]
Sorry it's not more dramatic in the pics. 8 weeks isn't much time to grow in the winter to show a vast improvement. I can look for other hoof pics that might better illustrate, if you like.