Consolidating similar tasks can be a timesaver. For example, consider the simple task of writing a letter: compose, type, and print a letter; make copies of attachments; type and print the envelope; fold and insert the letter into the envelope; run the envelope through the postage meter; and drop the letter in the outgoing mail. If you have several letters to do, would it save time to compose all of them at one sitting? If you have a couple of hours to concentrate, you may be able to accomplish more and better compositions (and if they are similar letters, you might be able to avoid re-typing each one by using a generic boilerplate or template and simply changing specific details). Then you could type, print, and post all of the documents in the same time period rather than doing a letter here and an envelope there, making a copy here and filing it there before starting the process again.
Is it possible to return several phone calls in the same hour instead of making a call, doing a different task, making another call, and so on?