I've never heard of such a thing, nor would I ever follow it.
That said, the only argument in favor of this, that I could imagine, is if someone is buying rigs that they are paying off over 10+ years. As a unit ages, you are going to start seeing more failures that require repair. I don't know what that 'sweet spot' is (and a lot of it probably depends on the payment schedule), but if someone simply wants to stay on regular payments and never pay a unit off, while avoiding the increased repair costs of an older unit, there is probably a point, somewhere in that 6 year range (or so), where the value and principal balance align in a way that you could simply roll those payments over to a fresh purchase.
Essentially, it would become a lease structure. Not what I would do, but I could see the justification for doing it in specific cases.
