This matches my experience. I have multiple demands on me, perhaps more so than many: multiple contracts, startup, founder/ED of a nonprofit that though not fully launched still takes time from my schedule every day, multiple creative projects, and some extremely unusual personal commitments that require that I work in smaller chunks than most people do.

The net result is extreme productivity and focus when I am working, punctuated with breaks that, while not always relaxing in nature, are completely different than what I'm doing when I'm working. My last employer, before I went solo, was stunned by my productivity. I'm not saying that to compliment myself at all, but rather to underscore what I think is the extreme effectiveness of this approach (I have found that if my use of this approach falls off, my productivity falls off). Focus hard for what is basically a sprint, and then do something else, ideally that you find relaxing. Then do it all again.

It's a modification of the work hard/play hard philosophy: Work hard, play hard, work hard, play hard, work hard, play hard....