[db48x]

Certainly. I get a lot more done on days when I work 6 hours than I do on days when I only work for 2. In fact, I probably get more than 3× the work done, which is nice. On the other hand, if I worked for 18 hours a day I would certainly not get another 3×; I would soon hit the point of diminishing returns. Where that point is must certainly vary from person to person, for I have noticed that it also varies from project to project and day to day.

Sounds to me like you need to reduce distractions rather than working more hours.