Can we just all agree that, unless they will actually hit them in the face, you don't have to hold doors open for other people? I'm getting sick of either glancing back at the person behind me, trying to calculate if they are in the 'polite zone', meaning that I have to hold the door for them, or running up a corridor to prevent the person who is patiently waiting with the door open for me from getting annoyed.
Let's just stop this now. It's getting silly.