Interesting discussion. time for my own rant
Recently been shooting some play rehearsals on a stage; those shots have been coming out sharp consistently. Infrequently have been shooting some headshots of actors; those shots have been disappointingly soft at times - arrgh.
This work is primarily with K5 and Tamron 28-75. My prep ahead of time is to take shots at home of some signs placed on my refrigerator with magnets. I try to adjust focus at about 8 to 10 feet away to simulate real world conditions. And its working successfully for my stage shots.
Didn't occur to me till now that i could have taken those headshots with liveview. In the discussion of mirrorless cams, occasionally see the comment, "why would anyone want to buy one". My Answer: Because i'm tired of playing around w/ focus charts - i just want to take pics.
Anyway, the ops point is worth trying. I'll see if it helps. Some folks have mentioned that lenses may focus differently at close distances than far distances, and turning off the in-camera microfocus may provide an optimum focus at all distances. Or there may be focus adjustment data in the lens chip that helps the camera. Wish we had more info from optical technicians that actually do this kind of work - may help clarify the discussion.
End of rant!