It is actually a very forgiving metric over a year because it is measuring only your own productivity relative to your personal trend. That includes vacation time and sick time, so the year smooths over all the variation.
Maybe he did do 5 weeks of work in 1 week, and I’ll accept that (a much more modest claim than the usual 10-100x claimed multiplier).
Not only that, I think you're misrepresenting his claim:
> I suspect I’m likely 5-10x more productive, though it depends exactly what I’m working on
1) He didn't say 10-100x
2) He said it depended on the work he was doing
Those seem reasonable enough that I can take his experience at face value.
This isn't about you pressure testing his claim, this is about you just being unwilling to believe his experience because it doesn't fit the narrative you've already got in your head.
What makes you think one year is the right timeframe? Yet you seem to be so wildly confident in the strength of what you think your question will reveal… in spite of the fact that the guy gave you an example.
It wasn’t that he didn’t provide it, it was that you didn’t want to hear it.