The vast majority of new releases don’t contain any new ideas. In fact, more than 95% of all non-fiction books ever written don’t contain anything new.
Reading 100+ Books a Year to “Upgrade” Yourself is a Complete Waste of Time
Zat Rana

“95% of books don’t contain anything new.” My question, though: how much of that “old information” do I already know? If I only know some of it, then reading a book with duplicate information would still be new and useful to me.