I don't know why are you being downvoted as these are famous rules and contributes to this thread. I saw rule 2. ignored almost daily at a job - putting caches

I don't know why are you being downvoted as these are famous rules and contributes to this thread. I saw rule 2. ignored almost daily at a job - putting caches where it doesn't matter, taking days on a feature because of analysis paralysis, colleges thinking about using int instead of Integer or not creating another function because of 'overhead'. I think these are wise rules - of course not when you use a 2 MB js library for an uppercase() function. That is madness. But the decision if you should use an arraylist or a linkedlist is unimportant almost every time. Of course there is that 1% when it matters and these rules are about the other 99%.