Maybe he's an expert at putting in subtle touches that few know about/apply to their own wheels. Potentially, there's a lot of variables involved here that we don't know about. He could be a perfectionist...and he probably loves what he's doing so he takes his good ol' time. I'd be pretty stoked on seeing/riding someone's wheel that took them three hours to build. I put in about an hour per wheel (without final truing), but in the back of my mind I imagine there's probably something else I could do to make it that much better...and this guy's probably doing it.