[Dave in MN]

Brent,
Specifically: Why raise and lower the engine rpm when breaking in? If done rapidly, from a high rpm by totally closing off the carb., it will draw oil into the rings and promote lubrication of the upper cylinder wall and rings thus reducing the heat being generated between these components.
I follow this practice.

All the rest? I basically agree with what you are saying.

I do have another purpose for running the long-blocks I build longer, as I am verifying them to be leak free well past normal driving loads by using a water brake/Dyno to load them. Doing this, I know when the customer picks them up that all is proper.
The customers also like the dyno report.

As to my driving and operating instructions when asked how to break it in: I tell them "Don't lug the engine" and repeat it two more times during the subsequent questions as we are loading the engine. Often, the last thing I say to them as they are departing is "Don't lug that engine!" rather than goodbye and we then both laugh. That's it!
Good Day!

BTW: I think Henry lied. I am seeing about 2 hp short on every engine I build that has close to stock bore, cam and original head. (Yes, I have had the Dyno calibrated.)