Far too much. If there's a crunch, deadline, tons of work that must be done immediately, it's all day if not all night. But I try to avoid that. If I've done enough work for the day, and particularly if I'm tired and sick of it all and put in enough hours that day, shut the computer off and don't think of it one bit. It's important for my work and my life and health to watch out for computer obsession.