It can't be that often. I just went through the Notes on HPMoR.com (which seem to be incomplete) and C-f for 'review', and nowhere since February 2012 does Eliezer ask for reviews (he remonstrates demanding reviews, mentions total review count, talks about reviewing his plans, etc.)
...Author's Notes for Ch. 18, 'Dominance Hierarchies':
Warning: Potential spoilers ahead if you have not read up to Ch. 18.
Two months. Over three thousand reviews. What can I possibly say, besides thank you?
Still, My Immortal had over eleven thousand reviews. You wouldn't want people to think that fic was better than this one, right?
Sorry about the pace slowing down. I started this fic partially to prove to myself that I could still write thousands of words per day, so long as I was doing something easier than the rationality book I was bogging down on. Now I
Master version: http://www.gwern.net/hpmor#analysis