A typical problem case is “Original Album Classics” from Molly Hatchet, there are five albums in there that all have own covers.
If I cannot put a cover to a disc but only one cover to all I don’t know which album I am playing at the moment. Of course I know but I cannot see it anywhere.
The only way at the moment is to split the CD box set into the single CDs and grab them but then it is not the 5CD box anymore in terms of metadata.