[OJFord]

But if nothing came of the 20% work, you could've done 25% more on the core job, doing positive performance things there. I'm pretty sure that's what's meant about it being a career dampener, not that it wouldn't be great to hit on something fantastic and accepted as a new core product with thousands working on it full-time. (IANAG.)

[oakfr]

Everything is obvious in the hindsight. 20% projects carry a risk, failing one or more 20% is fine. Failing many is seen as lack of judgment and does dampen your career eventually. My point was that, with reasonable judgment, an engineer can get good stuff done with a 20% project. Also, not every 20% project needs to become a fantastic new core product to be considered a success.