Not while its fresh. Not more than 1/3 to 1/2 its redline is perfectly fine for seating/bedding parts.That's not good for an engine. It needs to run through its entire rev range.
.. I think what you mean is that you dont want to keep a constant rpm during break in.. THAT is true, dont use cruise or keep same speeds for long periods while breaking the engine in as that practice can also cause parts to improperly seat and wear prematurely.
Some components seat and break in faster than others but for the most part the first 1k mi is a good well rounded number for a automobile application. Usually its a time frame of operating hours but no one has a hour meter in their car (though I think they all SHOULD have one).
You run a good chance of shortening an engines life by repeatedly running it hard without fully seating moving parts after assembly.
Performance engines are built with parts designed to take more abuse than a standard use engine. These take longer to fully break in because of their stronger material composition.
Bottom line, follow what the manufacturer recommends.. they dont make those statements for fun or to keep you from having fun, they do it to keep their warranty claims to a minimum.. aka.. getting engines to last as long as they should by properly breaking them in.