Just reading another thread about a lone woman in a hotel room being walked in on.
I've had the same experience three times. Twice I was away with work and the hotel gave the wrong key to someone so they walked in on me. The third time I was travelling alone and we both happened to get to the room at the same time to try to get in.
For various reasons I didn't do anything about any of those times.
I now travel with a door wedge but I do worry about getting out (or someone getting in) in an emergency.
(ETA- by wrong key obviously I mean they set the key card with the wrong room number or whatever it is that they do).