[andreareina]

That's only when the breakthrough happened and misses all the rest of the time spent on the problem.

[fredrikholm]

And nothing says they weren't thinking about the problem when it happened.

I've had a lot of "aha" moments not sitting by my desk, but that doesn't mean that I wasn't thinking of the problem. When people say they had an idea in the shower, I suspect it's precisely because they were undistracted enough to focus on the problem.