Either accepting or dismissing the number without understanding its purpose or source can also be arrogance, but I agree that throwing a number out without any additional data is of limited, but not zero, usefulness.

When I want to know more about a number, I sometimes seek to test the assumption that an order of magnitude more or less (1.5%, 150%) is well outside the bounds of usefulness—trying to get a sense of what range the number exists within

No, dismissing something that is claimed without evidence is not arrogance, but common sense.

I think we're getting hung up on the concept of dismissing. To question skeptically to learn more is different than to dismiss.

The 5 Step Design Process emphasizes making requirements "less dumb," deleting unnecessary parts or processes, simplifying and optimizing design, accelerating cycle time, and automating only when necessary.

Musk suggests that if you're not adding requirements back at least 10%-15% of the time, you're not deleting enough initially. The percentage is an estimate initially based on experience, and now for several years based on estimates from manufacturing practice.

Yeah, not sure how you'd measure this apart from asking people to tag feature re-adds. And all that will happen is that people will decide that something is actually a new feature rather than a re-add because the threshold has already been hit this quarter. Literally adding work for no benefit.

> How would you measure / calculate something like that?

SpaceX probably has stricter processes than your average IT shop, then it isn't hard to calculate stats like that. Then when you have the number, you tune it until you are happy, and now that number is your target. They arrived at 15%. This process is no different than test coverage numbers etc, its just a useful tool not arrogance.

I have no clue what you are saying. "They did it somehow"? How? Maybe they did not measure it, but Elon just imagined it. How can we tell the difference?