When I was writing my novel I averaged around 16 pages a day. On a good day I would pump out around 20.
When I write short fiction I usually keep at it until the first draft is done, so somewhere between 12 and 20 pages.
Of course, it always needs heavy editing. I usually do between three and five rewrites (and no that doesn't mean four smartass) before I feel I've gotten the story down. Of course my wife will always find at least one typo in my "final" version.