Many goalkeepers instinctively chooses to go backwards/outwards while taking a wing shot. In the beginning they correctly coves for an inside shot and forces the shooter to shoot on the outside. But if the goalkeeper - instead of attacking backwards/outwards - chooses to attack forward/outward they are able to cover the goal in a better way and don't have to move far to take the shot.
The drawing shows, that if the goalkeeper moves forward/outward (1), the distance from the pole will be smaller than if the goalkeeper moves outward/backwards. The 2 lines in front of the goal is the distance from the pole in relation to the body position of the goalkeeper while using these 2 methods. Forward (1) is the shortest line. Not much, but maybe just what is needed to take some extra shots.