At f/1.2 your focus should be dead on. If not, you need to use AFMA to tune it. Mine was dead on out of the box.
However, f/1.4-f/4 do experience some focus shift, but this is really only noticeable with objects closer than 1.5m. This is one of the casualties of a f/1.0-f/1.2 50mm with excellent bokeh. Even the $10k Leica Noctilux who many faint over has the same thing.
So, in short, AFMA your lens so f/1.2 is dead on, then just use caution stopping down if you are close to your target.