I've heard that theory/fact as well as not going down to 0, but draining to the teens, on a discussion group. I try to go down at least once a month to the teens on my iPads, & that seems to work. At least I hope it has been recalibrated. I try to to the same with the Fire. Your method may very well be what I should do. Have you had any problems draining the battery to 0?