On the flop we are much better off than on the turn.
This is irrelevant if we're putting it on the turn anyway of an unpaired board.
Cos can't really explain it better. If we assume a set with no other cards having been paired, that means there's 7 cards that can pair the board on the turn, so following Cos' way, he'll save the rest of his stack roughly 14% of the time in the tournament whereas you'll always completely do yours.