Like the article says, the point isn't that a locked door stops an intruder, it's that they're counted on to slow down an intruder for a minimum amount of time.

Like the article says, the point isn't that a locked door stops an intruder, it's that they're counted on to slow down an intruder for a minimum amount of time. If your security guard walks past a door once every 8 minutes (assuming it would take a minimum of 10 to pick the lock) and the door can actually be compromised in 15 seconds, you have a problem.