VTA my compromise in setting

Thanks for your responses 

My cartridge is a Soundsmith Carmen mkII the TT is a Merrill Heirloom and the tonearm is the Classic Six that does not have the micrometer .

When using an Azimuth gauge/block to check the tonearm and cartridge parallel orientation to the record the difference between a 140gr and 180gr is very small , I would say that it would be less than 1mm , but this has caused me to think about trying a 1mm mat and setting the arm for a 140gr record and using the mat for heaverier records bring the two just a little closer .  Will a 1mm mat withstand the use of being placed on/off frequently ? If you watch Peter Ledermann's  video on SRA I am probably close enough with leaving my setting using a 160gr record .

P.S. correction

Setting the VTA for a 180gr record and using the mat for the lower weight records. 

@vair68robert, set the arm for 180g.  Play a 160g record and then play it again with a 1mm paper makeshift mat.  See if you can hear a difference. . 

For the first time in a while I agree with mijostyn. And testpilot. I have very expensive cartridges and on-the-fly VTA adjustment. I also rely upon the amazing Brian Walsh to set up my tables. I have had the pleasure of having him to my home five times. Not once has he counseled me to adjust VTA depending upon the thickness of each record. Nor would I. The quality of the pressing far outweighs the importance of optimum VTA/SRA for each recording. Life is short. If you are so OCD as to desire to achieve optimum SRA for every record, good on you. It is a noble goal for sure. To draw an analogy, I know people who can not stand the thought of driving a dirty car for a single day. Or even driving a car with a dirty windshield. I once knew a guy who would get down on hand and knees with a toothbrush and detergent to scrub the tile grout in his kitchen immediately after hosting a dinner party. His wife divorced him, go figure. To each their own. Each of us needs to decide how to live and what is important and what is not. Sorry for playing armchair psychologist and life-coach.

My Grado cartridge is quite sensitive to slight variations in VTA.

Prior to Grado (started using Grado 20 years ago) slight VTA variations were not an issue with the Sure V15 III's I used from the mid 70's thru 1986.

Decks have all been Thorens/SME combos with the exception of a stock TD165 that I purchased to experiment with (most of the popular online mods of 20 years ago were tried).

My most used shim "mat" is a thin/floppy Fripp and Eno import LP that I purchased around 1977/78.

It incurred a bad scratch early on but for some reason (?) I hung onto it.

As an experiment try a thin LP as a "shim" mat to see what it does.

DeKay