According to Writer's Almanac, today is Jodi Picoult's birthday today.
Very successful and producing a book almost each year. She puts her lack of problems with writer's block down to having to produce text quickly in her job at an ad agency.
That's my experience too. If you only have half an hour to write something then you do it. It still might need fixing but that comes later.
Sometimes I think we lose the urgency when we allow ourselves all the time in the world to write.