Break-In. How Long?

Buddy ran his 512 (Source stroker) for 20 minutes at 2000.
Promptly took it to Luskville dragstrip in Quebec and ran 10.5 all weekend
Don Garlits said he and Cotton Owen would put a new 426 on the engine stand, set it at 6000 rpm and go for lunch. If it was running when they came back they knew they had a good one...i'm not that brave but i never baby mine either.