My focus up to this point has been 1840-1940 WW, and Commonwealth up to 1952. Logistically, this is helped immensely by having to use only one physical catalogue- the Scott 1840-1940 classic volume.

It is housed in Steiner pages ("Deep Blue"), although, within them, is a virtual "Big Blue". I keep a wantlist and "collect to the album".
I have been thinking, though, of expanding the general collecting year to 1950 or 1960 for all the reasons voiced earlier on this thread. And then I've already collected the easy picking stamps for the classical era for each country, and so find my stamp additions have dwindled.

It would probably be a variable cutoff for each country, depending on interest. China 1949 would be logical, but I also like early QE II commonwealth issues.
What is bringing me up short are the space requirements. My wonderful spouse has accepted the 6500 pages/44 binder Steiner classical era collection shelving space, but I'm not sure if she would be happy with a volume twice as big.

To that end, I need a more compact approach. I recently acquired the 1840-1952 Minkus Supreme pages. I may put my duplicates into it for 1840-1940, and then house the WW 1940-1952 stamps in there also. True,for more complicated countries (Argentina-watermarks), Steiner pages may still need to be used.
