My wife has a history PhD. For her quals, her reading list was over 300 books (okay, some of these were just scholarly articles but the bulk were books). To prep, she read about 2 a day with one day off per week for six months.
I just laugh when I compare my quals in CS, which was two tests each covering one textbook and a discussion of about 10 papers.
As a somewhat traditionalist physicist, and having grown up around university campuses, I love university libraries, and probably use them more than most scientists.
It was a bit of a revelation to me when my partner, a historian, casually complained about the limits on simultaneously checked out items being a nuisance. Until that point, I had always assumed that the usual limits for scholars at university libraries, often over 100 books, were just there to prevent extreme abuse, not with the expectation that anyone would regularly reach them.
This was my experience as well. Every single historian I know has piles and piles of books currently checked out from the library. And boy howdy are they unhappy when the books are recalled to be lent to somebody else.
I just laugh when I compare my quals in CS, which was two tests each covering one textbook and a discussion of about 10 papers.