Each oil pattern has a "break point" at which the bowling ball moves off of the most heavily oiled part of the lane onto the "back end". The back end is the place where the majority of the bowling ball hook is desired by an experienced bowler because it creates "angle to the pocket". Bowling balls that simultaneously (or almost simultaneously) hit the one and two pin on a strong angle (up to 6 degrees[1]) from the left side or the one and three pin from the right side are very likely to strike. A properly executed "pocket hit" causes the bowling ball to travel off-center through the pins driving these into other pins either directly or off of the walls on either side of the pin deck. It's the side-to-side "pin action" that creates a greater likelihood to strike.
The "Rule of 31" can be used to estimate the break point for different patterns (calculated as the distance of length of the oil pattern in feet minus 31). This value indicates the board on the lane at the end of the oil pattern that is approximately the break point.[2]).