Based on my experience, all you need is the Manhattan strategy guide set and the bundle of official materials that ETS publishes. That's it, really. Of course there are hundreds of other resources that people recommend, see eg www.test-study-guides.com/graduate/best-gre-books but you won't need it. Sure, doesn't hurt to spend more time but I don't think it will boost your performance. Stick to the leading resources and you will succeed if you study hard with just those.