I didn't use Zanki but used Brosencephalon and it sounds like a similar set up. This is how I did it: I would just make a "Current test" deck and a "review" deck. Then I would use the browse feature to search the big deck (Zanki in your case) and change cards into my "current test"" deck. Usually after/during watching a lecture at home. Use keywords to find the appropriate cards. Takes more time and thought than just going through them, but it also gives some of the making the cards benefit without actually having to make them. I would also delete out a bunch of the duplicates/redundant material. Then when done with a test move everything to the "review" deck. Might be unnecessary to have them separate since ideally you will be doing all the cards that are due everyday, but I found it more manageable to split them up that way.