I know every person I'm friended with on Facebook, though a few I've never met in person which is mostly fellow forum members.
I might post on a wall once or twice a month and its just to share something I found amusing.
A 12 yr old cousin of mine posts once or twice an hour. She can't brush her teeth without posting it on her wall.
Matthias08 is friends with me on facebook and wall posts ALOT.
Maybe you can ask him.