I was trying to read up on permutations, probability and combinatronics when I came upon this link – Taylor’s Law of Programming Probability.
The theoretical possibility of a catastrophic occurrence in your program can be ignored if it’s less likely than the entire installation being wiped out by meteor strike.
The important number here seems to be 100000000x365x24x60x60 = 3153600000000000, which we called c – the average number of seconds per mass extinction of life on earth. The reciprocal of this number, 1/c is the probability that all higher life on Earth will be wiped out by meteor strike in any given second. (The name c stands for the catastrophe number.)
There is just no point in worrying about anything that happens with a probability of less than one in c, because you’re more likely to be killed (along with the rest of humanity and most of the mammals, birds, etc.) during this exact second than you are to be bitten by your putative problem.