The way it should be done is first using a stopwatch for consistency. Run rich and undercompressed for a period of time - about 7-10 minutes. Lean out a d increase compression to clean up and build heat 1-2 minutes, remove fuel and allow engine to stop and completely cool to ambient temperature. Start procedure again.
The piston is wearing and particles shedding during the 4-cycle/rich mode. The piston is cold and not expanded. Excessive wear will damage the piston seal by wearing the piston too much. What you are trying to do is work harden the piston and liner bore and create a glass smooth surface. The return to 4-cycle rich mode and going back and forth never allows the piston and liner to completely cool which doesn’t allow the best cycle to complete. You start cold, work up to warm, then hot, then completely cool. Do this 7-10 times and then check to see if it will hold a lean flight setting without sagging. If it sags, do a few more heat cycles. The important thing here is the cycle of being cold, warm, hot, and back cold. This process is relieving the stresses in the piston and allowing it to expand and harden to its final surface which will then not wear much at all due to the surface of the piston and bore being so perfectly smooth.
That article does mention this and the reason for it.