The apprentice items is a pretty good way of looking at things and the bulk of the effort imo. In the long term consider that at some point you’ll be getting reviews for apprentice + guru + master + enlightened + burn in the same day. I see it as managing energy to learn new material and managing the available time to do reviews.
When I was at a higher level I think I spent like an hour and a half to two hours a day on reviews + lessons doing fast levels (I had a long commute on public transit which helped). At that point accuracy was really important since that meant keeping stuff out of the apprentice learning stage, so I found it really helpful to slow down and focus on mnemonics, reading out loud, ect. which in turn reduced the number of apprentice items.
IIRC, ~20 lessons a day when optimizing order is usually a 7 day level up. While I’m on team fast, I don’t think it’s necessary and many would argue against it. If you haven’t already read it, jprspereira’s guide has a few sections that cover the detailed logic if you want to fine tune the process. Otherwise, I think following a simple metric like apprentice items or doing X lessons/day are good enough for the vast majority of people.
Edit: I forgot, Kumirei made a nice little chart showing the impact of accuracy on reviews in her simulation thread