You are right that there's always going to be uncertainty. Perhaps it turns out that in practice, the uncertainty with this method is less than other approaches

You are right that there's always going to be uncertainty. Perhaps it turns out that in practice, the uncertainty with this method is less than other approaches. The point I was trying to make was about the different between incidental uncertainty due to imprecise equipment, and more fundamental uncertainty due to physical laws. For example, other intrinsic uncertainties are the Planck resolution for time and space, and the Heisenberg Uncertainty Principle for certain combinations of information. Similar to those, radioactivity has a fundamental limit. We cannot predict when an atom will emit radiation, all we can do is make a statistical prediction.