Why do we go to the elevator and push an already lit button? It's lit. The elevator is coming. It knows it needs to stop on our floor. There's no need to push it again. There's no need to push it 5 or 6 times in a row. That won't make the elevator come any faster. All it really does is frustrate us because it's not coming any faster.
I do this too. I push an already lit button, as if it will think, "OH!! SMurF pushed the button! I'd better hurry!"
So I make a decided, concerted, difficult decision to not push the button again. It's hard. It's an effort to stop myself. I want to push it. You know, just in case.