How to run the drill:
Each player must have a ball. The first player picks a spot to shoot from. After he shoots, the second player shoots the ball immediately afterward. If the first player makes the shot, and the second player misses it, the first player gets one point (The first player to 7 points wins). If the first player misses the shot, and the second player makes it, then the second player gets one point, and it is his turn to shoot first, with the other player now following him. If both players make the shot, then neither player gets a point, and they continue on.
Essentially, the player who makes the shot gets to shoot first the next time. Ideally, the players run the drill at a pace where they are moving quickly from one shot to the next.