There is a big difference between doing something that is a waste of a time and something that wastes your time.  It's the difference between drifting backwards or moving, if only painfully slowly, forward.  It's also the difference between doing an excellent job on the wrong thing or doggedly pursuing something great.

Many seemingly important tasks fall squarely into the category of "things that are a waste of time".  You can keep your desk perfectly tidy.  You can hold meetings with lots of ...