I don't have any particular resources to share on this subject (but there is much discussion on /r/anki and /r/medicalschoolanki about it). Broadly I'd say that the most efficient way to use it is to use it consistently, but not to make it your one-and-only practice. It's passive practice, and it's useful for making sure you see idioms and words that might otherwise be uncommon, and it's extremely useful as a searchable database once you've built up your deck, but it can get tedious, and drilling works better as a complement to, rather than a substitution for, practical experience. The move is to limit yourself to ~30 min a day, and use the rest of the time you want to spend on languages for active engagement, like speaking/writing with other speakers of the language, or reading things you're interested in in the target language.