Abstractly it's nice to know.

But practically does it really matter?

Even if we knew the case, one can't just e.g. whip 0.4x into 1x, so a 2x remains a very valuable 2/0.4 jump.

> Even if we knew the case, one can't just e.g. whip 0.4x into 1x, so a 2x remains a very valuable 2/0.4 jump.

This is pure speculation, which is why actual data would be useful. Is a measured 0.4x performer that way for innate reasons or is that something which some combination of training and mentoring, better tools, streamlined environments, etc. can help with? — or is the way that's measured even valid? I've seen a few cases where someone got flack for being slow until wider perspective showed that they were the only one solving the customer's real problem because it turned out that what they were doing was more complicated than it looked and/or the other guys were “solving” it in ways that required lots of ongoing maintenance.

>Is a measured 0.4x performer that way for innate reasons or is that something which some combination of training and mentoring, better tools, streamlined environments, etc. can help with?

For this or that individual (as per your example of "a few cases"), maybe.

For the majority do you think there will be something that hasn't been tried until now, what with all 2000 methodologies of management, team structure, company culture, development methodologies, tooling, agile, waterfall, and what have you, that will suddenly make a difference?

I think there are plenty of things which make a difference — for example the training and mentoring I mentioned — but the methodology point touches on the problem that they're neither cheap nor easy and most places are unwilling to invest in them. Very few companies which “adopt” something like Agile manage to substantially transform their culture because that's hard and it's a lot easier to make an announcement, do Agilefall, and avoid hard conversations.