Grit vs. grind in the professional world

I was pondering "Do Less. Do Better. Know Why." on my run this morning, and I kept coming back to another quote from Cal Newport's excellent post:

What separates the lauding of grit from the lauding of the grind lifestyle? This question is crucial to our mission here, as, of course, being happy and low-stressed is one of the key pillars of my philosophy.

After some thought, I arrived at an answer:

- The grind lifestyle involves filling most days with an unhealthily large amount of work. It treats the overwork itself as the goal, not its results. This chronic overwork, in turn, generates stress and deep procrastination.

- Grit, on the other hand, is about persistently accomplishing a reasonable amount of hard work. For example, consider my book writing. I spend 1 - 3 hours a day, most days, on this task. I’ve been doing this off and on for six years now. These are hard hours, requiring real hard focus. But they’re not many hours — so they’re not a source of overwork or stress in my life.

This makes a lot of sense, and it's easy to see how it applies to being a student, or personal hobbies at any stage of life. What I'm grappling with is how it can be applied to a more traditional professional career. Particularly as a manager, there are always fires to fight and lots of little things necessary to keeping the ship on course, and these are very difficult to keep "quarantined to a reasonable number of focused hours each day" (whether that's 1 hour, or 3, or 6, or 8, or...).

So, is there some way Cal's attractive philosophy can by applied to the task of leading a large team or organization? Or is this the part where someone says this advice is for students, and/or traditional careers are for suckers and this is why you should be a student/writer/public intellectual/serial entrepreneur?