I can't seem to get anything this sharp out of my 5D3-hmmm.Earlier on when I got my 5D3 first, may shots were not sharp. Some were due to not doing the AFMA and others were due to camera shake. I have doubled the shutter speed since and that helps. Also body sway while shooting wide open can mess things up so I shoot AI Servo many times.
That is so true! The first test shots were really disappointing! I did exactly what you did - doubled my shutter speed and AFMA'd my lenses...