If there is a possibility of several things going wrong, the one that will cause the most damage will be the one to go wrong. If anything just cannot go wrong, it will anyway. If you perceive that there are four possible ways in which a procedure can go wrong and circumvent these, then a fifth way, unprepared for, will promptly develop. Left to themselves, things tend to go from bad to worse. After things have gone from bad to worse, the cycle will repeat itself.
Nature always sides with the hidden flaw.
It is impossible to make anything foolproof, because fools are so ingenious. If the enemy is in range, so are you . Incoming fire has the right of way. Don't look conspicuous, it draws fire. There is always a way.