One of my more painful anecdotes goes like this: Years ago, we were coding a piece of government regulation that decides eligibility of some kind. The rules went something like this "if it's a man and over 60 or over 55 and part of these classes of occupation but not in .. or ... then .... If otoh, it's a woman and ... ". The law was written down in the exact same wording. We coded it in the same way 12 pages of conditionals split out into different functions to make it more readable. Then I came, armed with my knowledge of algebra, Cayley tables and optimization of boolean functions. I created a truth table for the boolean function at hand, optimized that function into a small equivalent expression and replaced the 12 pages of code by a one pager. A job well done.

Two months later the law changed adding a new special case somewhere deep inside. I could start over. Lesson learned: don't outsmart the logic of the business.