With thinking LLMs, they can think, but they often can only think in one big batch before starting to "speak" their true answer. I think that needs to be rectified so they can switch between the two. In my previous framework, I would say "would I be able to solve this if had all the knowledge, but could only think then start typing?".
I think for larger problems, the answer to this is no. I would need paper/a whiteboard. That's what would let me think, write, output, iterate, draft, iterate. And I think that's where agentic AI seems to be heading.