I use it at a one or two time application to grow back hair over bald spots. I also used it to treat a sort of dermatitis on the pasterns once. It works well for these applications, but it does smell....really bad!
When I was using it on the pasterns as recommended (daily), I noticed that after probably a week my horses seemed to have a reaction to it. They were stomping their legs and just looking uncomfortable, so I rinsed it off and they were fine. Although it didn't say so, I think you would have to wash it off almost daily to prevent this. It did treat the condition though.
I don't like it for the mane and tail because it leaves them very greasy, which in my experience, just leads to rubbing. It also causes huge flakes of dandruff.