I like booleans, sometimes when I'm starting those nested if statements, I'll just go ahead and take the cases, enumerate all of the conditions in a "truth table" and write code accordingly for each case. The best thing about this is that you see all of the cases and can spot the undesirable or invalid cases and plan for them. Just like the article says, you spot an odd case (door locked but open) and can get a "heads up". The only thing is that the article seems to be against booleans so watch out for just enumerating the cases you expect because as mentioned, those "door locked but open" cases could actually be possible but unexpected.
