I do this as well. Mine is to track actuals against my schedule. Helps knowing what I should be doing. It's just a habit now. It's all on paper though, no digital aspect.
I use anki with org-noter and the anki-editor minor mode for digesting PDFs, a sort of hacked version of incremental reading. I just stuff entire definitions and proofs into it and use cloze deletions for almost everything, then I attach a bunch of screenshots from the source material in the "Extra" field for any context when/if I fail the card. That, combined with the load balancer plugin and a limit of 5 new cards per day keeps my daily reviews around 1 hour. I have 18,000 cards. I'm familiar with the 20 rules for formulating knowledge but I just don't care to break things down into atoms. So I cloze and forget.