First test at 0, -5,-10,-15,-20, 0, +5, 10, 15, 20 4 clicks on each = 40 tests done twice = 80. Then 10 clicks either side of the sharpest value = 20 clicks. Grand total = 100 clicks per lens. I've tried my 24-70, 300mm f4, 70-200mm, 50mm f1.8 G, 50-500mm Sigma OS. So that equals 500 clicks minimum. Quite a lot plus target setup shots.
I have dismissed the Sigma results which I did at 400 mm, because of distance conditions. The 300mm and 50mm were fine (0 and + 1). The 24-70 and 70-200 are a nightmare as the results between minimum and maximum focal lengths vary so much that the results are inconclusive in my view. Yet, I have total trust in the sharpness and focus DOF images I take with those lenses in the real world.
I'm going to have to repeat the 24-70/70-200 tests again so I guess it will be 700-800 clicks total testing minimum.