Sometimes I think being smart is the ability to zoom in and zoom out. Or in other words, to shift between thinking micro- and macrocosmically on a regular basis.
Being able to zoom in is pretty self-explanatory. Attention to detail never yielded poor quality work.
However, being able to zoom out anchors your small tasks to larger meaning. The Muse, a favorite career advice blog of mine, published an article that advocates finding meaning in your work by asking yourself "Why am I going to be doing ___?"
Looking at the big picture can also help you to re-align your tasks with goals, reminding you to re-evaluate whether your current task at hand is worth pursuing further in light of those main goals.
It also helps to inform you whether or not a specific task is worth your time. Oftentimes, 95% completion on a task is sufficient, and I find that, more often than not, the last 5% would takes me the same amount of time it took to do the first 50%. At that point, some strategies I resort to is outsourcing my last 5% by seeking a professional opinion, for example.
Another efficiency strategy is knowing the value of time. I used to block out large chunks of time to study for exams, and that often yielded only about 25% of focused work. On the other hand, if I spent a day full of a variety of activities, I'd use the evening's remainder few hours on concerted and fruitful effort. I guess that why working parents can be very successful.