The thing with sport patterns is they vary dramatically based on the previous shot on the lane before oiling. If you have a center that puts out a THS all the time then on Sunday they decide to run a sport shot tournament or league, then the true nature of the sport shot will not be seen. It will be more difficult than the THS, but the THS and topography will prevent it from being what the sport shot was suppose to be.
If you are running the sport shot for multiple shifts and days, then each subsequent oiling will get closer to the true sport shot. This is one of the reasons why people will score better on the National's shot at their home center than they do at Nationals. Your home center has a shot history in the lane bed that prevents the occasional sport shot from being the true shot.
Also, if I remember correctly, the rule of 31 is a formulation for exit point from the pattern, not break point. Your break point could be at a different length. I see a lot of people throw their first shot down the middle, very slow and with a lot of side rotation. They will notice at what length the ball makes its change in direction and that will tell them the general length of the pattern. From there, I would suggest finding a line that gives you enough room at the after the pattern to get to the pocket and still able to throw the ball as straight as possible. This is why you play outside for short oil and inside for long oil.
