Wow you got me confused there Rob, but its all clearer now
Hasnt there been cases where the Seat tube is wider at the top and narrow further down, so shimming means that the narrower seat post still fits in the seattube whilst still being secure by the shim and clamp? If you follow?
I try an avoid shimming, it was always my thought that more surface area touching resulted in stonger fitment of said post? and not just 1 1/2" holding the post secure.
I'm sure there is a technical reason for shimming, other than to open up a greater selection of seatposts to use.
"Would anyone else rather be doing something other than marching up and down the square????"