One big part of managing your time is figuring out how much time you spend on each task. With a world wide web of distractions one browser click away, electronic organizing can take much longer than you expect.
With a paper planner, completing a task is as simple as pulling out your planner, checking off an item on your list, and making any notes that you need for later. There are no batteries to charge, so your schedule is always available. And you can take meeting notes without leaving an impression of rudeness.