Proper use of Schema.org “WebSite” type: apply it

Question

Should the "WebSite" and "Organization" types and their properties be applied to all pages of a website or just the homepage?

I have valid JSON-LD code defining the the necessary items for Google mobile search results, but I am not sure if it should be included on all pages or just the root/home page.

Answer 1

It would make sense to provide it on any page where it’s relevant.

For example, if this is an organization’s website, each page is about/from the organization, so provide metadata about this organization on each of the pages.
A consumer looking for structured data on a certain page is not necessarily also visiting and checking the homepage, so it might never learn that you are providing relevant metadata.

That does not necessarily mean that you should include the full item (with all properties) on each page. It can be sufficient to provide the full item only on one page (e.g., on the site’s homepage), and link to it (for example with the property author) from each other page.