Structured data should be appropriate to your content and not used blindly.
Also known as schema markup, structured data adds code via HTML to help search engines understand your page. This encourages rich results for your pages beyond plain URLs, titles, and meta descriptions. This includes a clean breadcrumb trail instead of a messy URL, or your whole FAQ page shown directly in search results, to improve SEO.
You may then assume more is better there, which isn’t true. For instance, in the past I had Local Business schema for my SEO consultancy, even though I serve clients nationally. Google did a frustrating but logical thing… it stopped showing my homepage in search results to instead focus on my Google My Business listing.
Other examples include marking up internal reviews or adding product schema for items that don’t exist. At best, Google just ignores your structured data. At worst, they apply a manual penalty that seriously harms all your keyword rankings.
Add relevant structured data to your pages when possible. Nonetheless, take a moment to consider if the schema is valid and the investment worthwhile. Otherwise, you incur an opportunity cost and may bring unintended consequences.