You and your project team will no doubt be tempted during the creation of each task to overstate the estimated amount of time for it to be completed. Don’t yield to this temptation. Always reflect the accurate amount of time it should take to complete a task. You can use PERT’s optimistic, pessimistic, and most likely approach if you’d like, but don’t inflate the time required for each task to allow for a mistakes, rework, and late activities within the project.

The reason is explained in Parkinson’s Law. Parkinson’s Law states that work will expand to the fill amount of time allotted to it. In other words, if your project team says an activity will take them 24 hours to complete, but they know the work will probably only take 16 hours to complete, it’ll magically take 24 hours. Really, it’s no magic. When people overestimate their time to account for expected troubles, just-in-case scenarios, and other time-munching issues, they rarely take advantage of the time they’ve created for themselves. They’ll find other work to complete or simply wait until the time they’ve reserved for issues has passed and then hop into the work and hope for perfection.

Think of your own experiences. How many times have you had some small task to complete but spent hours cleaning your desk, organizing your materials, and researching the best mode of attack rather than just hopping in and completing the assignment? But how do you work on the day before your vacation? You are able to complete considerably more work on that particular day because the tasks must be completed before you’re able to escape.