I think this is symptomatic of the philatelic situation in Poland & other communist countries of this period. Even though they were mostly commercially used, the stamps were basically propaganda items & hence not seriously studied at the time. Thematics were the big deal so you had endless displays of "Lenin & his Idea", Copernicus, Madame Curie, etc. to the point where you had booklets written on how to put together a Copernicus display & hence they would all look remarkably similar.
Looking at the only readily available Polish stamp magazine "Filatelista", there were countless articles on symposiums, meetings & their decisions & the like, in some issues there are barely any valuable philatelic articles apart from the new issues & the info therein would be taken as gospel without any further study.
In 1960 the 5-part tome "Polskie Znaki Pocztowe" was published, a seriously major work to be sure, but nary a word about the numerous perf. varieties of the mid 50s photogravure stamps.
It's only in the past 20 years that this material has been studied & catalogued & I'm sure that there is much more like the Dni Krakowa paper varieties to be uncovered. Apart from the "blocked " issues, these stamps were all commercially used & there's tons of them out there waiting to be studied, mine are sitting in a large box in my study.
Where they have been sitting for about 9 years.
Here's my Dni Krakowa page.