If you are struggling with Book 2 of Robin Hobbs' Assassin Trilogy, Book 3 is going to be impossible for you to get through. At this point, you have found out Hobbs is not for you and you can go on to other books.
My controversial opinion? I don't believe in a Literary Canon. There is not a single book or author that "everyone should read." Not Shakespeare, not Tolkien, not To Kill a Mockingbird, not anything.
Yes, some books influence others. However, you can enjoy, say, the Lion King just as well only knowing the general plot of Hamlet. Reading Hamlet won't improve your experience. Read Hamlet because it is Hamlet or not at all.