Putting in 25-30 good, quality hours at work each week and then 30 more hours a week on my pet project, I would not classify an hour as good depending on if I produced code or not. A good hour too me is one where I could keep my concentration on work, thinking or coding.

It's doable, working two shifts. It takes a 30 minute walk from work to home to reset and prepare myself for shift #2. If my boss want both those shifts though I shall ask for double the money. I don't see how I could be working any more. This is my max. Both shifts require a creative and hungry mind. I'm very hungry at the moment but I suspect this is a phase.