I have one more fun experience to share.

Back story is I'm the seasoned traveler, with an engineer from Philly traveling with me. At the time I was a multi year 1K, usually on segments, he on the other hand was a complete rookie with zero experience in the frequent traveler world. It was his first time flying via DEN, so I thought I would give him a tour of the airport, including other concourses. He kept expressing concern about getting back to our gate as it was boarding, and I kept saying we had plenty of time. What I didn't realize is that I was flying so much I had last weeks boarding pass pulled up in my Apple Wallet, not the current one. We made the flight, but were the very last to board.