If you’ve studied productivity, you’ll recognize the axiom above as Parkinson’s Law, the proposition of British naval historian Cyril Northcote Parkinson. The statement first appeared in a 1955 article in The Economist and later, as the basis of one of Parkinson’s books, The Pursuit of Progress.

To illustrate this principle, Parkinson used the example of an elderly lady who sets about writing a postcard to a niece. Since nothing else requires her attention, the simple task takes all day. She fills the time searching for stamps, looking up the niece’s address, worrying about whether the post office will be open, making a cup of tea, and discarding the original note to tinker with the language of the missive.

It’s easy to see how this example translates to emails, memos, and written reports in our workplaces. The impulse to give tasks more time than they require may be our desire for a bit of leeway, insecurity about one’s abilities or, it may relate to the idea that by taking longer, we will do a better job—although most people are limited in how long they can engage in purposeful activity without fatigue. Should we then impose strict time constraints on our work? Or that of those we supervise?

A relevant post on BBC WORKLIFE, addresses those questions and discusses Parkinson’s Law in more depth than I can do here. The article also quotes Princeton behavioral scientist Eldar Shafir on attentional fatigue: “Because our attentional capacity is limited, we divide it sporadically any way we can as we run through everyday life,” he says. Yet, now and then, we have to buckle down.

In his book “Scarcity,” Shafir and co-author Sendhil Mullainathan discuss the potential costs of laser-like focus: “When you have a deadline it’s like a storm ahead of you or having a truck around the corner. It’s menacing and it’s approaching, so you focus heavily on the task.” And while you may whip off a brilliant piece of work, problems can arise when all else is pushed to the periphery of one’s attention.

Plus, there’s a chance that pushing too hard, going too fast, can make us prone to errors in our work—just as it can lead to injury in athletic endeavors. “If your deadline is too short and you’re panicking…you might work inefficiently, and things might go badly anyway,” [Shafir] says. Ideally, we can find an effective way to complete our various tasks while managing both time and quality.