The problem with efficiency is that your reviews will pile up & up & up if you add too many cards too fast. In fact I’ve started taking short breaks in which I intentionally don’t enter any new cards so that I can clear out the backlog. Even if you spend 1 whole minute on each card, that is only 20 minutes per day if you’re following the recommendations & only doing 20 new cards per day.
The problem with efficiency is that your reviews will pile up & up & up if you add too many cards too fast. In fact I’ve started taking short breaks in which I intentionally don’t enter any new cards so that I can clear out the backlog. Even if you spend 1 whole minute on each card, that is only 20 minutes per day if you’re following the recommendations & only doing 20 new cards per day.