If it’s for your work then refer to your department SOP. Otherwise it is determined by your ammo, optic height, and optic functionality. KD zeroes are great for range confirmation but real world use should drive it, as well as your practice at UD engagement. Folks don’t stand upright presented like a B27 in reality.
Could be a 35 yard, 57 yard, or 100 yard. Who knows. Define the acceptable radius to do MPBR.