Index archives that satisfy a real intent
A curated category with original context, a clear topic, useful navigation, and enough strong content can be a valuable landing page. A nearly empty tag created for one post usually is not.
Control archive sprawl
Audit categories, tags, authors, dates, formats, search results, attachment pages, filters, and parameters. Merge redundant taxonomies, remove unused terms, and avoid auto-generating thin combinations.
Keep pagination crawlable
Paginated archives should expose normal crawlable links between component pages. Do not canonical every page to page one when later pages contain distinct post links crawlers need to reach.
Make a site-wide policy
Define which archive types are indexable, keep their canonicals and sitemap treatment consistent, and review them after theme or SEO plugin changes. Continue with the indexability checklist.