Even a more complicated pure strategy does not work. For example, suppose the kicker always shoots in the opposite corner to the one he chose last time. Then a future opponent studying this player would discover the sequence. The essence of good penalty-taking is unpredictability: a good penalty-taker will be one whose next penalty cannot be predicted with certainty from his history of penalty-taking. It does not mean the kicker should go left half of the time and right half of the time. After all, most kickers have a natural side and favouring that side gives them a higher chance of scoring. But even if you naturally shoot to the keeper’s right, sometimes you have to shoot to his left, just to keep him honest.