Even that strategy isn't enough. I bought a Retina MBP with Lion pre-installed, which was the only configuration they sold, so you'd think it would have been pretty well tested. It turned out that the Lion video drivers couldn't handle the retina display. I had full machine crashes three times a day. Others online had the same problem, and some who were beta testing Mountain Lion said the new video drivers had cured their crashes. As soon as ML was released, I took the free upgrade, and the crashing stopped.

I then upgraded my kids' Snow Leopard Mac to Mountain Lion so I'd only have one Mac OS to admin (along with my Windows, Linux, iOS, and Android machines...sigh). The Mountain Lion upgrade caused all sorts of headaches on the kids' machine.

Moral: The new Mac OS version you buy might not be compatible with your Mac, even if it's the OS that came with it.