I just tried doing the "All Buildables" thing in Tranzit, and the last thing I had to build was the NAV Table. Problem is, once it is built, you always have it, and you never have to build it again. AFAIK, there is no way to remove it either.

It doesn't matter, stop the timer when the last buildable that you can build is assembled.

Honestly the NAV table should be removed from the buildables list in the rules. At least in my opinion.