Are you saying that you do.
Well, I don't have a collection book or anything like that, but I often make a point of not throwing them away, particularly if the paper is nice and/or the typography is nice. A signature on a compliments slip is also good.
I have only seen the collecting of compliments slips written about by someone other than me in an article in a printing magazine in the 1960s.
Collecting compliments slips got mentioned in a chapter of my first novel.
http://www.users.globalnet.co.uk/~ngo/l … er_064.pdf
http://www.users.globalnet.co.uk/~ngo/novel_plus.htm
While writing this post I went and read the story from Chapter 51. It is over four years since I completed writing the novel, started in 2016.
William