[twayt]

You get the same result in a short span of time, heck you may even get a reliable error bound.

Where this falls apart is that error accumulates over time and not just for one heap of sand but for many such heaps of sand that also interact with other heaps of sand.

Predicting weather for the next hour is trivial. Aviation runs on the fact that you can forecast fairly accurately into the next hour most of the time.

The difficulty scales superlinearly over time due to the error accumulation over predictions