[y5e06]

While out on my run last night I was pondering the issues I'm having w/ my new clutch (arrghhh!). I then began to wonder, "How do race cars break in their clutches when they can't drive them easy on the street first?" So that then expanded to other items such as engines, rear end (gears), etc.
If the car isn't street legal, and you need to put in 500 miles or so on a specified part to break it in, what do you track only guys do? Are the items you use 'race only'? i.e. they don't require the same breakin proceedures and come near 'ready to use'? What methods are used on a clutch, or even an engine, when you can't put in those easy miles before beating on it?