When I played as a human I found that the most efficient way to win a game was to play like Pacman. It makes your opponent resign immediately. Methods that are shortest in moves are almost always trading risk for speed (or they could be improved by doing so), leaving your opponent with hope you will stumble. (E.g. he has still passers he can advance, while you are already busy driving his king towards a corner for checkmate ignoring his advance because the Queen will be just too late to prevent the mate. Capturing the passer produces an instant resign.)
Many times my team mates criticised me ("Why were you playing X? Y would have won much faster!") to walk back to the board for no other purpose than to shake hands.
