If anything can go wrong, it will. Nothing is as easy as it looks. Everything takes longer than you think. 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. Whenever you set out to do something, something else must be done first.
Every solution breeds new problems.
It is impossible to make anything foolproof because fools are so ingenious. If we have much to lose by having things go wrong, take all possible care. If we have nothing to lose, relax. If we have everything to gain, relax. If it doesn't matter, it doesn't matter.