A couple years ago while looking for GTD (Getting Things Done) resources, I ran across David Seah's website and blog.
Today I read a post of his about time and creative work. I have found, like he, that trying to break up creative work into hour-long time increments is harrowing at best. After reading this, it makes sense to find bigger blocks to do my studio work. I'm going to look back at this article if/when I look at readjusting my work scchedule -- if not to decrease my hours, then to simply shift things around to create better time blocks. Here's a link to the post, "Makers, Managers, and Getting into the Creative Box".