For creative positions I don't see hours/week as a useful metric for anything. Most of my time 'working' is not sitting at my computer typing or whatever.. it's thinking about things while laying in bed while I can't sleep or when sitting on the can or when taking a walk (etc.). Often my subconscious comes up with something while I'm not even thinking about it. So I'm working when playing games or reading as well. Working isn't labor, it isn't something you do. It is all about how much value you create.