Sarcher, you are absolutely correct that raising or lowering the VTA the same amount as the LP thickness difference will preserve the original alignment. There, I knew I would learn something and this is so obvious.
However, some of the people I know change SRA for different records by listening and trying to duplicate the original cutting angle. This is independent of record thickness as there is/was no standard cutting angle, though most I guess were around 92 degrees. For these people, changing SRA does indeed alter alignment. Perhaps to such a small degree that it is not an issue.
And as Audiofiel wrote, life is too short. I set SRA with a 150-160g LP and leave it, obsessing no more. However, I do spend 20 minutes per side cleaning an LP, because it sounds better to me, so we make our choices, even if they are inconsistent.
However, some of the people I know change SRA for different records by listening and trying to duplicate the original cutting angle. This is independent of record thickness as there is/was no standard cutting angle, though most I guess were around 92 degrees. For these people, changing SRA does indeed alter alignment. Perhaps to such a small degree that it is not an issue.
And as Audiofiel wrote, life is too short. I set SRA with a 150-160g LP and leave it, obsessing no more. However, I do spend 20 minutes per side cleaning an LP, because it sounds better to me, so we make our choices, even if they are inconsistent.