I'll probably end up around 8 or more hours today, including cube-related stuff online. But it's both a weekend and the front end of a vacation week, so I really have no responsibilities. Some days that I have a lot going on or a lot of work I don't get more than a couple solves in. I never skip anything to cube, although I frequently cube in order to put off doing my work. To put 8 hours in perspective, though, note that I'm also listening to music, IM'ing friends, etc. I also take lots of breaks, depending on how well I'm doing, my attention span ranges from around 20 to 90 minutes of actually cubing, after which I'll go find something else to do for awhile.