I think different industries might need different standards. I notice that after a day of hacking, I'm really productive for <i>at most</i> 5 hours at a time. Given some break times, I think 6-7 hours is about my sweet spot for getting actual, high quality work done.<p>The other 1-2 hours is lost in confusion, answering questions, being interrupted, forgetting what I was doing, surfing, etc.<p>One thing I miss about freelance was being able to work whenever I felt I would be most productive. Jumping into a problem from 12 - 4pm can be more effective than working 9 - 5pm.<p>Unfortunately for us, it really comes down to management, and all they usually see is $ / hour ratios. They don't really understand that productivity (in regards to programming) is not just, "how many bolts can this person tighten per hour." It's a complex problem for sure.