Agreed.
Since most people in the thread are discussing priority boarding, I guess I'll commit the same mistake ():
I was flying SFO-SEA-FRA, with SEA-FRA in LH F class, on a UA award ticket.
The evening before the flights, I changed to an earlier SFO-SEA flight, and received the UA confirmation and the receipt with the new e-ticket number shortly thereafter.
No issues checking in at SFO, and I received the boarding pass for the SEA-FRA flight at the UA checkin desk.
When I approached the LH gate in SEA to have my papers checked, the agent was having issues because while I was booked on the flight, the e-ticket number wasn't in my reservation. Apparently, the new e-ticket number hadn't been pushed over to the LH side.
The supervisor was called to the gate and they apologized profusely for the inconvenience. I was asked to take a seat in the cordoned-off area usually reserved for F class and HON. At first they didn't say what the issue was, but once I figured out that it may be something caused by my late change, I gave them the new e-ticket number. After about 25 minutes (and telling me every 5 minutes that they would make sure I would be able to travel), the agents managed to get everything synced up.
When boarding was about to start, the supervisor apologized again for the inconvenience and offered me to board first. After I boarded, it took a couple of minutes before the other four F class passengers boarded (and I saw them at the gate right before I boarded, so it wasn't a case of them not being at the gate).
That's how I got my "extra special" priority boarding before the other F class passengers.