How Does John Piper Prepare a Sermon?

I guess when you have been writing sermons for over 30 years it wouldn't take you as long. Piper doesn't look at the passage till the Friday before: How Does John Piper Prepare a Sermon? :: Desiring God:

I don't work on it until Friday. I pick out the title and text either weeks or days ahead of time because I have to get it to the worship guys by Tuesday. But I don't study it, and I don't write or work on a sermon until Friday morning. I devote all of Friday to sermon preparation