[mkartic]

My interpretation of that rule. I think the author is only asking readers not to goof off or postpone work that can be right away. Like mentioned very often, getting into the right context for a task takes some time. So working till 8.15PM instead of leaving at 8.00PM, but completing the task at hand is better than having to come an hour early the next day. I find that even very incomplete insignificant tasks keeps nagging away in your head until you actually get around to do it.