When I'm on a new project, I also goof off for a few days at first, sometimes up to a week. Then I crunch out a lot of code fast.

I don't really mean to do it that way, and I usually feel guilty during that first week. But apparently my subconscious brain is sorting things out. I try to work and it all just seems too hard and confusing. I make little attempts to start and they just seem wrong. And then one day everything suddenly clears up and it's all obvious.