Thank you for the kind remarks. Here are two threads, one testing the contention that the microfocus adjustment (MFA) isn’t useful because it’s only correct at one FL: https://www.uglyhedgehog.com/t-508300-1.html.

And another showing Focal’s facility to plot aperture vs acuity (and some results that are contrary to the idea that the sharpest aperture is always 1-2 stops down from wide open). Even though MFA and Focal isn’t applicable to MILC cameras, I wish they’d make this utility available for them - it tells you in a minute if that lens you just bought is up to snuff, where it’s really the sharpest, and when diffraction begins to have a noticeable effect: https://www.uglyhedgehog.com/t-573232-1.html

If your in-out focus data is gathered from the image sensor then theres no reason for focus errors. OTOH, if its gathered from some other source such as a Leica rangefinder or an AF SLRs AF module, those other sources are only analogous to the real image focused on the sensor. There is artifice involved and thus a possible difference between the analog and the reality.

Any AF calibration performed will be to deal with the difference between the non-sensor focusing device (Leica RF or SLR AF module) and the actual sensor image. IOW, you are calibrating the bodys own internal focusing device, but nothing in the lens.

The only focusing info that comes from an SLR lens is the light beams coming thru the glass. Theres nothing within the lens to calibrate. Its the bodys assigned job to determine when those light beams are in focus. The body will ask the lens to move, and when the body sees in-focus it tells the lens to stop moving. Any inaccuracy there is the bodys error.

(With Leicas the lenses are also calibrated cuz the RF is just a mechanical position measuring device, it doest see any light from the lens).

Many experts caution against fine tuning a lens, or, if you will, lens calibration. Most calibrations can only be done for one specific distance, many, many folks who try to fine turn end worse off than before calibration.
Over my 50 years of professional photography I have never had to fine tune a lens, be it Canon, Nikon, Sony, or Hasselblad.
I now only shoot mirrorless, which focuses the image right on the sensor, no need for any calibration for any lens.
I caution anyone trying to calibrate, DO NOT DO IT.
Lots of folks here will disagree with my statement, but after 50 years of hanging photography, and after more than 500 weddings, I have never, NEVER, had any issues with not getting a tack sharp image.
If you know what your doing, you will NEVER have to fine turn a lens.
Goodbye.