The structure data is scattered all over the place. This does the very important thing of aggregating them, and bringing them together. If you had to manually do that it could take weeks.
Of course it’s not the kind of question you can get an objectively correct answer for, but you could come up with the correct answer for a given methodology.
Especially in cases such as this. For well known works of literature and music structured data exists already.
You can only correct for missing entries by doing the same work you’d need to start from scratch. But after that you now have a second list to consider.