Just write away freely while you're in the zone, but accept that it's a rough draft and that you'll have to go back over it with an axe a time or two and show no mercy for anything that's just padding.
Otherwise, write as much on the page as you need to to get the needed information across with clarity. Keep in mind you don't have to end every page with a choice though and so if you're worried it's a wall of text situation, look for a natural place to split it off to the next.