I am not confident that whatever caused JWT to take so long will be solved for the next project. NASA by its nature does not really benefit from "scale". Every important thing they do / produce is novel.

I am sure they have learned alot from building JWT, as they certainly learned a lot from building Hubble or the space shuttle. I don't think that knowledge necessarily transfers forwards to make the next project easier.

Well, as you seem to have said, NASA doesn't seem too interested in scaling but rather in doing things that stretch the bounds. If their goal isn't to scale the previous project but to push past what people thought were possible with experiments, that seems OK to me.

IIRC the companies that made the beryllium main mirror went bankrupt because the material is much more tricky then anticipated.

So you would have to do that again basically or come up with another mirror design.

Ah I hadn't know. That being said, perhaps one thing they learned from this is which materials they may not want to use again in the future. I dunno, I just struggle to imagine that they didn't learn a lot from this and that most of us have really any idea whether the learnings are worth $10B, $1B, $100B, etc.