I fully understand your concerns, as I'm sure many others have. I would attribute the "fast" progress to many things the main one being not having to hunt for content (what was cut)as all of that had already been done. Also a big chunk of Narshadaa had been done by a very talented guy ,SWfan28 and Zbyl as to when this was compled I don't know,it could have been made 2 years ago. So of course that was a big timesaver as well as some other content he did as well as jinger letting us have his enclave mod.
The other thing is we are not so much as trying to "fix" the entire game as we are adding content so it makes sense and not break anything. (we are trying to fix broken stuff as we go).
Another big thing Zbyl and I work well together(so far) there have been no arguments about how something is added or how a scene should go. There are also some other factors such as there are alot more rescources of all kinds of modding information availble now that wasn't around years ago.