You can literally measure anything, that’s not the same as being 100% precise. That’s how it works.
In much simpler form, it's similar to the "Where will this satellite in a decaying orbit land?"
The difficulty is not the approximation: the difficulty is that whether drag begins to increase at t=x or t=x+30sec (based on orientation when it first encounters atmosphere) cascades throughout the rest of the equations and dramatically changes the results.