User blog comment:Ducksoup/The Future of Infoboxes on Wikia/@comment-4522253-20150829132801/@comment-24473195-20150829142459

It is reset by cache but it maintains its own separate listing and cache process. For example, opening a link such as http://dbz.wikia.com/wiki/Saiyan?insights=withoutimages, editing and saving the page will immediately invalidate insights cache if  someone added an image recently (i.e. the article already contains an image).

In any case, the insights list is buggy. It is only showing portable infobox pages for several wikis, so it may not work anyway in its current state.