Why should you pursue efficiency? Everyone has their own reasons, and I’ll give you one of my reasons: efficiency allows me to make the most out of my time. As a result, I have extra time to pursue learning projects and time to relax (downtime allows for relaxation, which I believe triggers moments of pure brilliance). As Peter Drucker (look him up) put it, “There is surely nothing quite so useless as doing with great efficiency what should not be done at all.”
This previous point is important: being efficient does not mean cramming work into every single one of your waking moments — that is called stupidity. Humans need moments of relaxation and rejuvenation in order to maintain their highest levels of ability. If you try to follow such a foolhardy course, you will run headfirst into Stein’s Law: “If something can not go on forever, it will stop.” You can not go at full-speed indefinitely. Efficiency is about picking your moments of intensity and focus. Don’t run yourself into the ground.
Finally, let me tell you one way how efficiency should not be used: efficiency should never be used to justify laziness. You should never use efficiency principles to explain why you only put in minimal effort, explaining that the Pareto Principle demonstrates that the results-to-effort ratio is markedly higher in the beginning of starting a task. While it might be attractive to use basic optimization models to justify what really is your lack of will and drive, life doesn’t work that way. No one is impressed with your results-to-effort ratio; people only care about your results. Using “efficiency principles” to attempt to justify mediocrity makes a mockery of the discipline.