I disagree. First off, they are not shims, they are pocket facings.
Second, like I said earlier, one facing is required to protect the rail. So, by your definition, ALL tables are single shimmed, which does not sound right. That implies that no pocket facings are the standard table.
You can even see Brunswick table specifications, for pockets openings, require the facing to meet the spec. With the facing removed, the pocket is too big.
Shimming implies the table was tightened more than the manufacturer intended and one facing was intended for protection.
Anyways, one facing is a non shimmed table. Adding one additional facing would be the first layer in shimming so, two facings is a single shimmed table, IMO
BTW - I had a Gold Crown with no facings on it. The cornor pocket rails were butchered

The wood was all splintered and the cushions were coming off from all the high velocity impacts

I wanted to strangle the person who removed the facings when I saw the damage!