I'm sure I'm not the only one who doesn't actually post the vast majority of posts I write (not just on this site, by any means).
Usually its just "do I really want to get into an argument over this, when, given this site's demographic we are never, ever, going to agree on it?"
Other times its "reading that back I realise I don't really have anything to say I'm just jabbering for the sake of it".