I like counting the number of times my documents are checked.

In the Montreal airport you have to show your passport, boarding pass and US immigration form after leaving the check-in area. After waiting in line for US immigration, they check your passport and keep the immigration form. Walk twenty steps and you have to show your boarding pass before entering the line for the security check. They check the boarding pass again as you go through the metal detector. Present boarding pass and passport before going down the boarding ramp and present boarding pass once again as you enter the plane.

A colleague jokingly told me about the safest airport in the world. Two months later, I actually experienced it. This was about three years ago, so it may have changed. I forget if it was Des Moines or Kansas City, but as you enter the gate area you show your ID and boarding pass to a security person who dutifully checks it and hands it back. Ten paces away, you hand your ID and boarding pass to another security person who checks it and hands it back. I had to ask, "Um, why are you checking it if that person just checked it?" In a bored tone she replied that she was checking for something different. Sigh