The absent-minded professor There are three variants of procrastination, depending on what you do instead of working on something: you could work on (a) nothing, (b) something less important, or (c) something more important. That last type, I'd argue, is good procrastination. That's the "absent-minded professor," who forgets to shave, or eat, or even perhaps look where he's going while he's thinking about some interesting question. His mind is absent from the everyday world because it's hard at work in another. Paul Graham, Good and bad procrastination procrastinationproductivity
Solution to evaluation and back again A second reason the systems engineer’s design is never completed is the solution offered to the original problem usually produces both deeper insight and dissatisfactions in the engineers themselves. Furthermore, while the design phase continually goes from proposed solution to evaluation and back again and again, there comes a time when this process of redefinement must stop and the real problem be coped with—thus giving what they realize is, in the long run, a suboptimal solution. Richard Hamming, The Art of Doing Science and Engineering: Learning to Learn Co-Evolution of Problem and Solution Spaces in Creative Design