I just wrapped up another site review and the best performing pages are averaging about 300-400 words which is not alarming to me. This isn't the first time I have found this type of situation. Why do these light content pages perform so well? Because they satisfy users. For example imagine an online calculator page. Those pages don't usually have 800 or 1000 words per page. They tend to have a few hundred words and a functioning calculator and perform well.
I've actually come across sites that got penalized for boosting their word counts. In one situation they were blindly trying to make sure every page had at least 1000 words and that lead to ugly keyword stuffing, horrible usability and a total nightmare to their rankings. After we reworked the content to make it appropriate for human users, the pages rebounded.
I am not advocating people chase after short content but rather that we use common sense when trying to figure out how much content is the right amount. Using common sense, if you are writing a webpage on a complicated topic, it probably will need a big amount of content (you might even want to split it up between a few pages).
So what do you think? Why do you agree or disagree with me? What has been your experience?