There's a difference between running at low power settings during break-in, and running at low power settings after break-in.
The PDF attachment cited above specifically refers to engine break-in, not to normal post break-in operations.
The other link in the same post shows yellow settings which at first blush would suggest a caution range; this is not the case. The yellow, as indicated in the link, represents lower airspeeds...and does not denote an unfavorable operating range.
Again, more information is required.