If you are just now starting it for the first time, you can run it briefly, but that pertains primarily to break in. I would guess that it's tied as much to breaking in the cams & seating the rings properly, which probably needs to be done at moderate, normal operating rpm moved up and down some. Not held at a constant idle. I'm sure that there are more technical reasons, but this is what I've always been taught on car engines.
FYI, I don't know what you are using for an oil to break in with, but from what I know on cars now, all of the cam manufactures warn against using your typical motor oils for break in. There are now addititives and such that will result in a flat cam very very quickly on automotive engines that are assembled with brand new cams and standard motor oils.