Nowadays players should be stronger and fitter so they have no excuse, except when the manager tells them they need a rest... In our team the only player who really plays as though it's his last game is Kuyt, other than that the rest of them should have no problem playing two games a week. There is no incentive to play well, as you are likely to be rested for the next game if you do well, so why bother putting in the extra effort?