The point of this is that regardless of how many times you have studied a book. No matter how many times you have chosen a key verse or outlined a book, there is still more to learn in the text. The more familiar with the book you become, the more you soak in the text, the more and clearer you will see.
In just about every workshop I lead we use 2 Peter. I have lost count of how many times I have studied that book. Yet every time I return to Peter’s words I see something new. That is the depth of this gift that the Lord has left us. We will never, no matter how long or hard we try plumb its depths.