The specs they prefer are closer to the tight side then loose side. For instance, you have a crank bearing that has to be between .034-.046 (not real numbers) 22re Performance will build their engines closer to the .034.

That's not really "tight" that's just to spec.

The bearings have very little to do with the main issue with "break in" - it's the rings and cylinder walls.  The rings, bore spec, cylinder wall cross-hatching, and RA are the machining part, then the HOW the engine is run for the fist 20 minutes or so is critical.  Then it's acceleration, WOT, RPM range, and deceleration while the vehicle is being driven that is most important for a good break in.

That's just my worthless opinion.

Gnarls.