Should You Use Only One H1 on a Page?

Yes, ideally you should have one H1 on a page and this should be the main page, post or article title. If the page is a list of articles, the page title should be h1 and each article (post) title should be h2.

Web publishing software generally lets you use mutiple H1 tags throughout a document in the same way you can use multiple subheadings (h2 – h6) in any order if you wish. However using heading tags semantically (so one H1, followed by subheadings H2, then H3 if subheadings within the H2 section and so on down to h6) creates a proper structure. Which is logical and helpful to SEO and Accessibility so is recommended.