I ride the bus into work, and the bus will not stop at every dropoff point unless someone wants to get off. You can pull a cord that makes a sound and (usually) lights up a sign before the next stop if you want to get off.
I prefer not to pull the cord. I just let someone else who is getting off at my stop do it for me. But there are rare times when no one, or very few people, are getting off at my stop. So how long do I wait until I can't stand it anymore and I have to pull the cord? I usually can last longer than most people, so it is rare I have to pull it. Of course, I don't want to wait so long that it makes it hard on the bus driver (like if he is in the wrong lane).
I think it would be an interesting psychological measure to see when a person tends to pull the cord. Someone should do a study. Not me. I'm too busy resisting the urge to pull the cord.