I manage about a book a week reading for a half hour or so at lunch time. It's not usually heavyweight stuff - fantasy, historical fiction, sci-fi, on my kindle. But hey, it's my lunch break, right?
Gosh, I'm a slow reader. Usually when I read books (mostly non-fiction) it takes me a few days. If I just partitioned it to 30 minutes at lunch time like yourself, it would've taken me two to three weeks to read The New Jim Crow!