If you are manufacturing cars, there is no point doubling down on manufacturing doors or steering wheels if the rest of the car isn’t being produced at the same pace. “Understand the goal” and “don’t optimize sub-systems” are thus key principles in operational effectiveness.
These principles have powerful life lesson equivalents. First, they ask the question – what is the car equivalent we’re building in our lives / what are we optimizing for? And, what is the right amount of production for each of the aspects (work, home, social or however we define them) in our lives to build it well?
Second, they speak to the futility of comparing certain aspects of our lives with that of others. Unless we’re optimizing for the exact objectives someone else is optimizing for, there is no point comparing the sub-systems.