Use of mats for VTA?

RE:"Do you swap the mats in conjunction with a VTA adjustment on your tonearm or do you use mats alone?"

I adjust as best I can for average thickness recordings with the tonearm(ie-spacers for RB's, sliding pillar adjustment for the Linn & Tabriz Zi, double adjusting collar on the Artemiz,etc).I only change mats for instances where the thickness of the recording is causing a noticeable negative sonic effect.
I'm presently using a Dynavector Karat Nova whose stylus profile is not particularly VTA sensitive.
In the past and when I used the mat exchanging ploy to greatest effect was while I used Benzes and VdH's with their ultra sensitive Gyger and VdH styli.
best,
k

Can you swap mats while the record is playing? Just kidding. Would be sort of like that trick were the tablecloth is very quickly pulled and all the china and things stay on the table... trouble is the spindle, I guess. More seriously, this seems like a simple and ingeneous solution to the VTA issue.

If you want to really fine tune VTA by this method, Ringmat sells a set of variable thickness VTA shims. Supposedly really good, as they should be for the fairly outlandish price.

How about sheets of mylar in varying thicknesses. Just cut them to shape yourself. Should cost next to nothing.