The obvious answer is no "It should not happen" but think about this, there is now in place a practice called risk management.
With risk management all the adverse options, the possibility of things going wrong are weighed against the costs to rectify/prevent.
Mostly bean counters have the final say and that is why these things that shouldn't happen do so.
In other words it is cheaper to let it happen, occasionally, than prevent it.
The same logic is applied to maintenance, don't pull it apart and rebuild it wait until it fails.
If you read the reports into accidents/disasters they invariably shouldn't have happened, but it was too costly, meaning it effect profits, to prevent it happening.
But hey what do I know????????????
A stitch in time saves nine, not no more cheaper to new one.