The dock allows you to adjust focus at four predetermined distances. Since I posted about my initial experience with the dock, I've actually made an adjustment to the furthermost focus distance on the 35mm, as I found it was slightly front-focusing at distance. The dock enabled me to change only the furthermost setting, leaving the closer settings as they are, because they were already fine.
But yes, I know what you mean. My decision was to use the dock to make relative adjustments as above, plus global adjustments to all the distance settings only if the lens was clearly out of step with the rest of my lenses. As it happens, my copy is not out of step with my other lenses. It requires no AFMA on my 5D MkII, in line with most of my other lenses. On my 7D, I settled on -3 AFMA, which didn't surprise me as more of my lenses seem to require a little correction on my 7D compared with my 5D MkII.