Even before hearing this story, I used to religiously check that any door I entered while straying from the beaten path (urbex, or simply exploring infrastructure not meant for the public) wouldn't lock behind me. I've stopped myself from entering a stairwell a few times because I wasn't sure if there'd be another exit I could take. Occasionally, if I'm feeling daring, I'll pull out one of the blank plastic cards from my wallet and jam the door latch with it, then keep going.