How often is the IUPAC Goldbook Updated?
As various users have contributed to the arrival of this answer, it goes to the  community.

Firstly, the IUPAC is the authority of chemistry, which decides on and accepts terminology for international compatibility so that information can be unambiguously expressed by researchers, scholars, educators and students. So, it can be finally concluded that unless it is IUPAC approved, it is not official terminology.

Secondly, since the IUPAC is an enormous organisation, dealing at a global level, it can be understood that changes will be a little delayed as the information has to be checked for authenticity and a common end has to be reached. For example, it took quite some time to decide on the newcomers of the Periodic Table(Elements of Atomic Number 113-118).

Thirdly, a lot of terminology has a very limited scope and can be at the very least left out. For example, the iupac tag was dropped due to its limited scope.(See comments above).

Lastly, I thank the community for the comments which have fabricated the "bonds" of this answer.