It's just common courtesy to do it. The only time I don't is when the next person is quite a ways away, or I don't notice someone behind me. I always apologise in that case, though...
The worst thing is when you expect someone to hold the door open for you, and that 'someone' slams the door on your face.
What a complete moron!
I have manners. I believe manners are extremely important. It just makes me feel good to be nice. I'm a woman, but I'd still hold the door open for both guys and women.
I try to keep the door open for as long as possible.
maybe I shouldn't have done that on the Submarine trip I went on lol.