EDIT : So, this is the best resource that there is https://meta.stackexchange.com/a/59418/200868 I think that we need to create a more detailed post rather than refer to an answer that was written 2 years ago, probably at the time tag wikis were implemented. There is much more data available now, many more samples, and many more sites.
Tag wikis vary greatly within sites and from site to site.
- Is there any standard format that they should follow ?
- What content should they ideally have ?
- Should they delve into directly related topics (when highly relevant) ?