Efficient is a term that can applied to one of many things. A company can be efficient at increasing yield in one set of things while dismantling quality, longevity of workers, morale...etc. Being an "efficient" human being, IMHO, means you take advantage of your emotional well-being and take care of it so you have the ability to be productive and produce quality work. I always cringe when I hear about managers who are looking at only one or more metrics like sprint speed, output velocity, issue metrics, or profit margins alone, one or more of these don't necessary imply quality. To the same extent, you can't be totally undisciplined that you are always distracted either.