Please provide detailed explanation why the last third is not relevant in determining the amount of break.

If we took a 4 foot putt on a 9 stimp green, a 2% slope requires an AimPoint of 1 inch outside the edge, if we took a 10 foot putt across the same slope, it would break approximately 8 inches. Without going into the mathematics involved, this highlights that the final section does not influence the overall break as much as people think, the middle section is key to finding the amount of break for each putt.