... at least based upon the catalog values of the stamps. If the stamps are of nominal value used, then presumably they were used in large quantities, so why don't we necessarily see them very often still on documents?
This is similar to the threads I've made about Scott #J68, the half-cent postage due, of nominal value used, yet try finding one on cover or card paying a fractional cent rate. They're tough; any example is a $25+ item, with solo usages potentially climbing much higher.
I've posted about the paradoxical rarity of Scott #RD1 (1-cent Stock Transfer) on document and how Eric Jackson mentioned searching for years to find one for a client but never did.
I recently had the opportunity to search through several thousand stock transfer slips from the 1920s to 1940s, and it's not just RD1 that is rare, but also the 1940 1-cent "SERIES 1940" overprint, Scott #RD42. I don't just mean as solo usages, but in ANY capacity, meaning the scarcity can't be rate-based.
The scarcity of RD42 on document is interesting to me possibly even more so than RD1. There were numerous printings of Stock Transfer overprints of various denominations in the 22 years between RD1 and RD42. Was a 1-cent denomination even needed in 1940, or was it a statutory requirement?
I think an interesting task would be to go through off-paper used examples of RD1 and RD42 to determine WHEN they were used, to see if there's any pattern of usage.
I won't extend this contention of scarcity into the 1-cent greens, as those are bit modern for my focus and I've not examined any significant amount of material from that era.
There SHOULD be a lot more of these 1-cent stock transfer stamps on documents, but why aren't there?
Another document type that while the stamps catalogue a bit more, they still don't seem to appear frequently enough on documents to align with the catalog values, are "Memorandum of sale of tobacco" (example below) with tobacco sale tax revenue stamps affixed (Scott #RJ1-RJ11).
The stamps themselves don't catalogue much used. The entire set of RJ1-RJ11 is valued at $36.45 used. The aggregate catalogue value of the stamps on the document above is $40.15.
But darned if these ever appear on the market with any frequency... I've been looking.
So are there any other document types that, at least based upon the catalogue values of the stamps themselves, don't seem to exist with the frequency they should?