Because if you're trying to write and you have unlimited time, you can procrastinate an unlimited account, but if you have limited time, you rush to the page trying to get something down in the little bit of fragment of time that you have, and you may write a great deal that way.
“I think that by following the route that I have tried to outline, one gets into a much more interesting and productive series of questions than those that result from saying simply that Chinese don't like milk because they don't like milk.”