Every photographer does.

The time we didn't bother to stop the car. The time we didn't feel like changing lenses and nailing the shot. The time we knew we should take our camera with us and didn't want to bother with it.

Actually though, some of our best work is still on the negs or computer, that we haven't spent enough time with to make a great print of. Or somehow passed it by completely when we were editing.

Those ones are the real tragedies because we actually have the shot, we just don't know it.