How to find/list all per-post instances?

For a long-established site with dozens or hundreds of posts and pages, how do we find all instances where Simple CSS was used to customize that post?

Seems like a double-edged sword – great that Simple CSS keeps per-post customizations loading only on specific pages and not site-wide, BUT it’s also a nightmare trying to go back and update or remove CSS that was added sporadically across the site.

A central listing of all places where it was used would be amazing.