I think everyone has a good point for not prepping, but as someone argued, it's all about confidence. I know I'll feel more confident about 1L having had some background. Plus the stuff is fun for me, so the worries about "a waste of time" are off the mark in my case.
I bought E&Es in every subject save for Con Law (which I feel confident about): Torts, Ks, Civ Pro, Crim, and Prop.