I too don't really see the need, but something like irfanview can easily be used to create a contact sheet of all the cover.jpg (or any differently named file) in the library directory.
Simply search for image files (limit dates or just the whole directory), create thumbnails, then use the contact sheet output setting your preferences as to number per row / column etc.
It only takes a matter of a few seconds.
You'll then end up with something like:
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