Ok. I see you adjust azimuth with the help of a tiny bubble level on the shell and by ear. Not good enough for me, there are different views on it. Alastair Robertson-Aikman, the SME man, considered it a secondary adjustment and designed the SMEV with a fixed headshell. For fun I have used professional Bosch laser tools for set up and alignment of cartridges - I project the superimposed laser lines on the wall and measure the angle with an angle meter having a .05 degree accuracy. Audiophile crazyness can go up to that ... BTW the small bubble level supplied with my VdH Stradivarius was wrong by .9º.
Surely people can object that the test LP can be wrongly cut and inaccurate - I have read objections in this sense, but I own three independently issued test LPs that agree perfectly.
Most times I do not use measurements or objective data as an aim, but as a tool for guidance and confirmation - I find the pure subjective tools time consuming and sometimes unreliable.
I primarily use the mirror and then record the angle by making a note on the bubble level. The key is to do it by listening as the final judge.
we all choose our instruments. The ear is a very accurate instrument. I like making note of where the bubble is on the head shell relative to the mirror after I have adjusted by ear. The bubble and the mirror are starting points but mostly the mirror.
The current SME arms were designed with the assumption that the industry would adopt a standard for instance 9.5 mm for mounting screw to stylus distance. Also accurately made cartridges for azimuth. This did not happen so it is nice to have some adjustability. You seem to have moved on from the SME V arm. I have also, but I suspect for different reasons.
you are fond of saying we are governed by preference. What if we prefer a setting different from what the measurements dictate? I rely on listening, but of course I made mistakes in the past and I’m still learning.