Is there a way to list all used & unused views in site? or in panels? (as fields are listed in /admin/reports/fields). I have some complex sites with a lot of views (pages, blocks, entityreference, panes, etc.) and panels pages. While building a site we all make views to test something, then clone view, etc. at the end i may have a lot of unused views, i'm trying to delete unused views to clean site, all my views are rendered inside a panel page. I run D7, but i think this will be helpfull also in D8
I think this module might help you.
Module provides administrative page with detailed information about each display use cases and its status for each enabled view. It helps you to detect unused and broken displays to modify them or completely remove from your site.