From a weblog post (via Anarchaia) comes a fascinating story:

“Do you guys know Fermat’s Last Theorem?”

[...]“Everyone here knows that is it is Prof. Andrew Wiles who spent about 10 years to prove it. The final proof from him came in publication in 1994”

“It is correct. However, do you guys know how Prof. Andrew Wiles found these 10 years to dedicate himself to the Great Fermat theorem?”, he signed, “Prof. Andrew Wiles told me by himself, in order to focus on the proof of the Fermat’s Last Theorem, there was one year in which he worked extremely hard to write 20 papers and locked them up in his desk drawer. Then he would pick up two to publish each year. In this way, he gained precious ten years to allow himself to do nothing else except Fermat’s Last Theorem”

Unfortunately for me, this does not imply the inverse: spending 10 years on something does not guarantee that anything even remotely useful comes out ... but still, if this is true it's quite an amazing example of focus and perseverance!