The answer is it depends on the rocker being used. Most aftermarket heads use a shaft location that copies oem architecture and is (was) designed for a shoe (paddle, scrub) type rocker with its geometric point of rotation (which changes through the sweep) at the contact between rocker and valve tip. When you replace that with a roller tip rocker the point of rotation moves to the center of the wheel and now doesn’t change through the sweep, necessitating a different shaft location than oem to obtain the most beneficial geometry. In Mike’s tech page 2 he discusses why 1/2 lift method is now the accepted norm, and why “auto manufacturers and elite race teams” have abandoned the 2/3 rule of setting up geometry as it was a method of minimizing scrubbing with the focus being on longevity and wear not performance.