It seems feasible if you don’t imagine they’re all big novels. A lot of nonfiction you might borrow several of in one visit and not read front to back. Think recipe books, handicrafts, anything along those lines. Could also be smaller things like children’s books, poetry collections, etc., or some of the books were unusually expensive.

This made me curious so I looked a bit into it. Seems that milquetoast as an insult originates from an old comic character of the same name, and it’s at least feasible (and perhaps likely) that said character was named after milk toast.