When I get in the flow, writing software, I get a day of work done per hour. When I do 5 hours of focused work, I do about 2 weeks worth of work. The slightest distraction throws me off, though, because the context-switching becomes enormous. My favorite (yikes) distraction: having a tool I know and use not be available because of outdated company policy. This throws off everything and loads Anger and Frustration 3.7 in the brain processing center.