I think it's kind of difficult to go by number of pages with the line spacing and font and all. I only do about 500-3000 words in a sitting, but then I comb through that later and pepper in some pretty words.
But I have to be in the right mood before I start. This sounds ridiculous, but most of the time I lie down as if I am going to take a nap, and I imagine a setting...then put my characters in there and watch what happens when I get to that dreamy state before sleep. When something strikes me, I get up and see if I can fit it in the story.