We all make mistakes sometimes. Much as it would be nice to be right all the time, the margin of human error is a large one. Everybody has bad days, gets brain fog, or simply can’t be bothered to give 100% to whatever it is that they’re doing all of the time.
The seriousness of doing something wrong is on a massive sliding scale. Unless you’re a big time subscriber to the Butterfly Effect, it’s probably not the end of the world if you forget to put your soda can in the recycling. Make one wrong move as a brain surgeon, on the other hand, and you’ve got a much more pressing problem on your hands.
Many failures sit somewhere in the middle of the two extremities, especially when it comes to matters of design. It’s amazing how many times people don’t seem to think things through when it comes to feats of architecture and engineering. While they may be frustrating, at least this can also be amusing.