In basketball it used to be bad form if your team was well in front, and still put up a 3 point shot to end the game. It was essentially a gentleman's agreement not to rub their opponents faces in it.
In more recent times though, teams and players have come to realise that percentage points can be the difference between a spot in the Finals, and Mad Monday. So now even if up by 20, you'll see players in the NBL, NBA etc actually putting up shots at the end to blow out the score even more.
In professional sport, never take your foot off the pedal. Always floor it.