It is not enough that the reader does not spend too much time reading and commenting on Hacker News. Because willpower is a depletable resource, it is also necessary that the reader does not expend too much willpower resisting the impulse to spend too much time reading and commenting. When the "get back to work" page comes up, I find that I have to expend real willpower not to click on the override link (anchor) at the bottom of the page. To balance that change, you might simultaneously put a link to the reader's user page, so if he really needs to, he can go to his user page and turn the procrastination preventer off. (A logout link on the "get back to work page'd be nice too.)