Estimation may appear to be a very dry subject and overkill for trivial tasks. However, it is a very important step in managing expectations and creating realistic daily task lists.

An estimate is only a guess. Sometimes, it is an educated guess; sometimes, it is a calculated guess. In either case, it is still a guess. It becomes useful and effective when it is backed by plausible basis and reflects reality.

Any estimate could well be a number taken from thin air unless it is close to the actual time. An estimate can only be validated after the task is completed. A good estimate is within an acceptable range, for example, 5 percent or 10 percent of the actual duration of the task.

Why should we estimate how much time a task should take? For one, doing so helps us create realistic to-do lists. For another, it helps us see how well we are managing...