Brandon Sanderson notes on his blog (somewhere) that the usual is 1000/day to be expected as a writer, though I don't believe he specified if that was what he did or as a general rule, and he may be averaging that out to include revision time. I've read a transcript of a conversation with L.E. Modessit Jr. and he said about 2500/day for him. I forget if that was 5 days/wk or 7. I myself (when I get 2+ hours) can do about 1000, unless I'm really stuck on something.