"If you don't find yourself in need to add back at least 20% of what you removed, you didn't remove enough". Elon's word. Sounds like an excellent engineering principle, with some caveats of course.
I talked to a McDonnell Aircraft structural engineer in the 80s. He said something like Old Man McDonnel told us to design for a 0.85 factor of safety on the F101. If anything broke during testing, we'd redesign it.
I'm not sure if that was how it really worked out.
Then you are wildly mistaken about the field of engineering.
Imagine needing to add back 20% to a bridge because you removed too much, or a rocket ship, or a team of nuclear scientists (like is actually the case here).
I'm looking forward to Elon applying the same strategy to aviation. I wonder how many crashes it'll take for him to realize that this is a horrible engineering principle?
That's as much as an "engineering principle" as him thinking minimum character level of an item is more important than the actual attributes of the item in PoE2. He's just saying stuff his target audience thinks are smart, and whenever checked on it he lashes out. He's got nothing.