For Purdy the best type of practice was playing over master games and below is his method:
1. Play one side only - usually the winner's side if the game is not a draw.
2. Cover the moves with a card in which a niche is cut out of one corner.
3. Think out each of your side's moves before you look at the game move, taking as long as you would in a match game. Use a chess clock if you have one.
4. Having thought of your move, actually make it on the board.
5. Then slide the card over until you see the move. If you guessed differently, find out why your move was bad.
6. Look at the opponent's move immediately. For one thing it may assist you in discovering some fault in the move you chose.
According to Purdy, it is absolutely necessary to play over games if you want to become a strong player, and this is Purdy's way to get the most benefit from this exercise.
