I want to know exactly how much percentage I have before my battery dies, i.e. measuring the remainder of a finite resource AND estimating rate of depletion.

I don't care if my signal is -65 vs. -66 dbM, because that's largely out of my control and polled every 5-10 seconds, so even if I did choose to use that to try and find a better signal, the response granularity isn't enough to help me make a decision before my call is dropped.