Breaking in a race engine?

Check out hundreds of Youtube dyno videos of race engine builders. After cam break in they check everything before doing their dyno pulls. And they dont go to 3000 RPM and "baby" them. If you buy a dyno tested engine, the rings have already seen the stratosphere before its even shipped to you. Agreed, this is controlled and a little different from abusing an engine with 0 miles. By babying I mean it doesnt take 800 miles. Accelerate and decelerate a few miles and go. Thats what we always did on our sportbikes as well.