This is frustrating and I am mostly disappointed in myself. The images are out of focus. What f stop and shutter speed are required to test a D800 for focus accuracy? On a tripod with a 2 second exposure delay?
I tried the flat target scenario at the request of a famous Nikon blogger and I was told I did that wrong too. But I felt less bad after hearing that 40 percent of the people who followed the "Smith" protocol also were incapable of a proper flat-target test.
It is in fact possible to discern a camera problem without a certain test condition. To claim otherwise is to say the camera can work properly only under that condition. If I posted shots praising the camera showing the images in focus would you also say I have not proved the case given there was no flat target?
I'm now 100 percent satisfied that there is a problem. I've tried shooting under various conditions and see the same result. The focus offset is reduced with focus fine tune. Reliably. That I was so insecure I needed help to tell me that my camera was malfunctioning is a bigger problem than the camera.
P.S. in review mode and in Nikon software the focus point can be seen, so it is in fact possible to determine what the camera thinks it is focusing on in the absence of a flat target. It also states the focus distance.