I do appreciate what you're saying, but with this kind of thinking, where do you stop? Yes you can do defense in depth and defensive programming and all sorts o

I do appreciate what you're saying, but with this kind of thinking, where do you stop? Yes you can do defense in depth and defensive programming and all sorts of nice things. But if you tried to do this for every scenario all the time, you would never get anything done. At some point you need to trade off being productive against well pretty much anything else, which is basically YAGNI, i.e. do enough but don't go overboard.