If you decide to get into the elevator, even though you know that it's going the opposite direction, you don't know if it will continue doing so or not. If someone else has pushed the summon button in the anti-your-convenience direction, you will be taking the scenic route. I've known that for awhile. I take it into account when deciding whether to get into an anti-directed elevator.
What I did not know, and was amused to learn, was that if nobody has summoned it further away from the direction of your dreams, it will sometimes, for some elevators, perform the following little dance.
You enter the elevator and press the button for the floor you desire.
The door closes.
There is a pause while the elevator checks to see where it will open next, in the direction that it is going.
There is no next floor to open at in that direction.
There is a pause while the elevator changes direction.
There is a pause while the elevator checks to see where it will open next, in the new direction that it is going.
The nearest floor that has summoned it, is the one it is currently on.
It opens to let you in.
It pauses to give you time to enter.
It closes and checks to see where it will open next.
If no one else has summoned it, and there is no one else in the elevator who has pressed a destination button, the elevator proceeds to the floor of your choice.
I tried to be annoyed that the elevator opened twice to let me in, with a big pause to slow things down, but I couldn't be anything but amused. It was almost like being fussed over. Are you sure you made it in? Yes? We can go now.