People tend to check in during these times:
Less smell than main library.
Great spot to visit when you are looking for a quiet place to study for exams, complete homework or do some leisure reading.
Get a card for your kids. They don't pay late fees!
Ordering books from other libraries on sfpl.org and picking them up here is the way to go.
my favorite hideout. p.s. believe the hype, Zeitoun by Dave Eggers is a beautiful read, despite how much subliminal messaging on MUNI will convince you otherwise.