An opportunity to make overtricks should not be overlooked, especially at pairs scoring. If you are declarer you have a big advantage over the defenders in that you can see all of the assets of your side, which can give you a chance to put them under pressure - here is an example from a Congress pairs event.

A brief auction left South in three no-trumps on the lead of the heart five. Declarer played the four from dummy and won East’s jack with the queen. Declarer could now count 11 tricks, five in spades, two hearts, three clubs and a diamond, so began to wonder about finding a twelfth. By conceding a trick, one or both of the defenders might have a problem and not wanting to shorten his holdings in any of the suits, declarer decided to give up a trick early in the play. So he crossed to the club king (so that the suit would not be blocked) and led a small diamond towards his hand. East was worried that if declarer held the diamond queen and slightly stronger clubs, ducking might lead to conceding all thirteen tricks, so he went up with the diamond king. As you can see, later the queen of diamonds dropped under the ace and declarer had his extra trick. The overtrick gained N/S a 90% score on the board.