It's actually Brandon Melton's method. He is a AE/Reedy/Jconcepts factory driver.

I'm not sure. I do know that some people have a rich bottom end and a lean top to compensate. When this happens you need a higher idle. You can end up with to much fuel entering engine and the engine will need to burn that fuel before coming down to idle. This causes what I call run-on. The engine doesn't come off of high idle to low idle right away. That is why a proper idle gap and tuning the bottom is so important.

I'm sure someone else can explain it better or different.

You want the engine to come off high idle and to go to a low idle really quickly. Other wise the car will feel like it's pushing.

I've never experienced this. I have had good engine tuners with me all along. I've learned from them. I'm still developing my ear to the engine. Feeling what the engine is asking for. It does talk to you. It comes with experience.