Out of thousands of comments made about the PAC expenditure story, this one on Balloon Juice is my favorite:
Roger Cadenhead, who posted this, is someone who has churned out a large number of computing books, many with titles like Sams Teach Yourself Java 2 in 24 Hours or Sams Teach Yourself Java 2 in 21 Days. As a software engineer, these titles make me doubt Cadenhead’s credibility. It might-just-be possible to learn a substantial amount of Java in 21 days (it is a very large language once one counts the libraries), but I don't know any non-trivial computer language in which most people can be fluent in less than six months.
As the author of more than a dozen Teach Yourself Subject in Refreshingly Short Time Period books, I occasionally get sent the link to Google director of research Peter Norvig's essay Teach Yourself Programming in 10 Years and Abstruse Goose's comic strip on the easiest way to teach yourself C++ in 21 Days.
I'm currently working on Sams Teach Yourself C++ in 24 Hours, so these guys are hitting me right in the meal ticket.
The official reason for the titles of these books is that each chapter is designed for readers to accomplish in that time period. So if you read Sams Teach Yourself Java in 24 Hours, and I strongly believe that you should, you can read each chapter and complete its projects in an hour. The same goes for Sams Teach Yourself Java 6 in 21 Days, but you get one day for each chapter because the material is harder. Whether you complete these books in 24 consecutive hours or 21 consecutive days -- or space it out and take breaks -- is up to you.
The unofficial reason for the titles? If I called my next book Teach Yourself C++ in 10 Years, it would sell as well as Lose Weight by Watching Your Diet and Exercising Regularly and Become a Millionaire by Working Hard for 40 Years and Saving Your Money.
The Norvig essay ends with a line that my publisher should use on the next edition: "[G]o ahead and buy that Java book." -- Peter Norvig, Google