Originally Posted by Jagboi

Not always possible and can be entirely out of the passengers control. As an example, I flew LHR-YVR-YYC. Somewhere between check in and the gate at LHR a family had lost their passports, so their baggage had to be offloaded. We lost our takeoff slot and there was quite a delay leaving. Had headwinds to YVR so the flight took longer than normal. Landing at YVR, I have to clear customs and bags are reclaimed in the customs hall and have to be rechecked for the domestic flight. With all the delays, the normal check-in window for the bag drop for my domestic had passed, so they told me I had to go landside and see the agents there.

So I go landside and see the check in agent. They phoned the gate to see if boarding had started and it hadn't. They looked at the empty security line and asked "Can you run?". I said yes, and they said to go to the gate and they would take care of my bag. Both bag and I made the flight, but there was no way I could have made the check-in cutoff any earlier.