^ If you're leasing to own maybe...? What if you are just leasing to ride/show it? When I leased a horse this past year my eventual goal wasn't to buy him so in our contract we just said I would get any money I had paid ahead (which I only did month to month) back if he was out of use for months or what have you, UNLESS he was injured/died while I was with him and/or it was due to a direct result of something I did.
I will say though, the people who I leased from weren't horse folks, they were total newbies who leased him to me because they had their hands full with an intermediate horse... so maybe they didn't do the "usual" thing, but I would set up my lease that way if I were to lease my horse out. It's fair.
Proud owner of 13yr old Paint Gelding, Bali! <3