You only do that once

There are some things in your life that you may look back upon and say "I hope I never do that again". All too often, you look back and say, "I really should have known better."

Once case in point. I had the keys to a new home where the garage was detached from the home. Now, I didn't know the neighborhood and so out of an abundance of caution, I locked the door behind me. When I came back to that door 15 minutes later, do you know what I found? None of the keys that I was given unlocked that door. $125 to the locksmith.  Thank you very much.

Needless to say, I now double check the keys before I lock any door the first time.

You only do that once.