Open-ended time frames are a good way to make predictions and insure you can never be proven wrong.
Specific exceptions are often used as a tool in misleading attempts to disprove a general occurrence.
As the physicists have noted for nearly a century, you take any radioactive isotope, and it is impossible to say with certainty that a particular atom of it will undergo the fission process, but collectively, you can predict with a great deal of accuracy that a certain number of them will.