[kohanz]

I think using a start/stop timer is selling yourself short. Almost every programmer has ebbs and flows between thoughts and output (e.g. writing code). When I take a brief break from coding to check my e-mail or something, it's not like I stop thinking about the program I'm working on entirely. I don't think I would be nearly as productive over the long term if I just stared at my IDE for all hours of work.

Often a solution to a bug that I was working on the previous day will come to me during a morning shower, and I think it would be ridiculous to bill for those kind of events. That's why I tend towards the conclusion that the breaks and what would be considered "observable, verifiable" work tend to balance out.