Break in periods are largely pointless with the precision that components are made to and assembled these days. The main point of the break in is to allow minor imperfections to gently wear away and for parts to "wear in" to each other. I would agree with @
dirtymax that an engine should be broken in the way it will be used. Maybe the first few miles ever put on the car you should be careful just to make sure that nothing was wrong with the car.
Personally my car had 24 miles on it when I bought it and I regularly push it very hard, ever since the test drive. I am curious to see if there's anything that will come up that could be attributed to a hard break in. But it will probably be hard to determine since it could also just be a result of being daily driven by an overly enthusiastic driver.