If we are talking about the adjustment (and not semantics between the terms sra and vta) my experience shows it to be a rather important part of setup calibration for carts with advanced styli profile types...
I prefer to call it VTA. While important for initial setup, I have not heard any difference when adjusting it beyond that. I have adjusted mine in .001 in. increments through the full range my equipment allows, .395 inches. I cannot say it improved or became worse with the vinyl that I own.
As for adjusting for different thickness of each record I find that there is, in my collection of 300+ albums with 30 random measurements, an (average) difference in thickness of.022inches.
On a 9 inch arm little change in VTA from one LP to another. 12 inch arm well...
If you can hear this then you have far better ears than I. I'm not doubting what you wrote in the least. I'm just saying I have not been able to experience that.
Cheers!
