There are many theories and not much real proof in the realm of "How to properly break in a new engine".
Here's some advice from an engine builder.
Ford Strokers Break In Procedure
Myself, I operate the engine easily for the first 500 miles using break in oil and letting it go through several heating and cooling cycles and RPM ranges without any WOT runs. I am also a a magnet fanatic. I run one on the bottoms of the oil pan sumps, use magnetic drain plugs, and use one on the filter. Those metal particles are much less harmful stuck to one of the magnetized areas than circulating through your engine.
I change the break in oil out at the 500 miles and replace it with whatever I have decided to use. From there on I drive it like I intended for it to be driven. For the first 2-3 oil changes I change at 3000 mile intervals. After that I either change the oil when it appears dirty or at 5000 miles. With some synthetic oils this can be extended to as much as 15000 miles, but that's scary long to me.
When I say "appears dirty" I mean when it turns black from use and contamination. Sometimes this will happen sooner than the scheduled oil change interval because of driving habits or situations. City driving in stop and go traffic and short trips will contaminate the oil much quicker than highway driving. Therefore I will change the oil sooner than the scheduled interval.