For the last 1.5 months I tried to maintain on 20 lessons per day, with this I can get 8-10 day per level. Number of reviews nowadays is on 100-170 
and I’m sure it will increased when these item start enlightening & burning 
20 lessons per day sounds scary for me at the beginning for the first 3 months I did lessons irregularly, sometimes none, sometimes 10, and so on. But I got pretty good insight in how to reach a reasonable speed efficiently at this masterpiece: My Journey of 368 days (+ The Ultimate Guide for WK 📖 ) - #2 by jprspereira