2020 marked the
50th anniversary of Canada's 1970 Christmas stamp issue.

This issue most likely contains the largest number of constant plate varieties of any Canada stamp set. For the "flyspecker", it is a goldmine.
https://adminware.ca/1970The above is a link to a new resource on this set of stamps (to mark the 50th anniversary). If you have any interest in these 1970 Christmas stamps then there are a couple of items here that will keep you busy reading for quite sometime. Fascinating stuff.
In addition, there are over 45 different hi-res scans (600dpi) of full panes of stamps ... download and look for undiscovered and/or unknown plate positions of varieties.