A famous college basketball coach once told me that he had a strict post-game rule for his players. When the game was over, whether they won or lost, he wanted them to shake hands with the opposing players and then leave the court as quickly as possible. A player can say the wrong thing to a reporter or get into an argument with an angry fan or fraternize with people who don't necessarily have his best interests at heart. They're always better off in the locker room with their teammates. Nothing bad ever happened from making an early exit.
Entertainers adhere to the same rule.
The best ones always get off the stage a few moments before they've worn out their welcome. They know it's better to always leave the audience begging for more. Just as you never want to be the last person to leave the office Christmas party, you also never want to overstay your welcome on a sales call. But you can take this principle even further. Another CEO I know credits his success in large part to his ability to make an early exit from situations that aren't working out.