One big fallacy of the thinking man, perhaps not logical, but essential: Thinking too much. Some are so good at thinking that they can fool the rest into believing that they are living in the real world.
I've never checked if this story is true. But it sounds like something Aristotle would do, so I believe it. ;-P
This is why deadlines are useful. The customer cares what was delivered, not how exquisitely sculpted my code was.
So the acme of skill is to nail the 80% of the challenge that is readily automated, eschew the yak shaving, and then maybe "polish the cannonball" if the problem comes 'round again.