When my sister was in the fire academy, there was a nearby hotel slated to be demolished, so they used it for training. On one particular evolution, the task was "Search this whole floor for victims". The first door was locked, so they forced it (not an easy task with hotel doors designed to be reasonably secure), and then proceeded to break down every other door on the floor (20 minutes later, they're completely spent...).

Turns out, the instructors had only locked the first door, and they hadn't bothered to check any of the others, just assuming they were also locked.

Always, always, always try before you pry.

But that's not as fun..