I doubt that the phone's manufacturer would say that rooting is the way to properly calibrate. In my experience, the method I mentioned works well and is the proper and only way for stock phones. The battery stats are correct as soon as the battery is charged fully. Can you explain how your method's "instant calibration" works and why it takes 2 days? It's true, the phone should prevent the battery from behind discharged (or charged) to the point where damage occurs. I should have said that people shouldn't try to somehow overly discharge nor should they try to run the battery down quickly. And on the other side of things, leaving the phone charging for extended periods ends up cycling the battery thus shortening the battery's overall lifespan so that's not a good idea either. Yes, I think Verizon recommends doing it every month. It stands for Preferred Roaming List or something--the phone's knowledge of the cell network or some such science.