Also consider that many break-in processes include altering engine rpm with THE NEEDLE valve. The idea is to heat the engine up and cool it down, all with the needle valve, not the throttle. Adjusting the mixture instead of just moving the throttle insures the engine cools properly from the inside out, not just runs at different speeds.

Can't remember ever seeing a mfg suggest, ".......alternated throttle settings as per instructions," in their break-in recommendations. It's common to see them talk about using the needle, however.