I know, and I'm saying that 2x claims should be interpreted as an actual 20% increase, and 10x claims as an actual 100% increase. People are just bad at estimating their own productivity.
Ya, I feel 10% to 50% increase seems more realistic, when I see 100% to 900% increase claims it seems a bit extrapolated, at least I don't feel I'm seeing it at my work. And then it depends if we imply a given feature/fix/enhancement takes half the time as before, or we imply that we can get twice as many features/fix/enhancements done in the same amount of time as before. Those are not equivalent. I think the latter might be more accurate as to how it helps.