The last rack plays different

I've been thinking about how the final rack in a game of Scrabble feels like a different sport than the first seven racks. Same letters, same arithmetic, but suddenly every point matters more because there's no next draw to fix your mistakes. It's the same with those last hours of the day — you know you've got no more tiles coming, so you start playing the scores that are already on the board instead of the ones you dreamed up.