I've had galaxy 2, 3, 4, 5, 6, and 7 and never used one. Never scratched the screen. Ever. But it depends on how you use the device and what environments it's subject to...
HERE'S a thread in the Note 7 forum regarding your exact question. It would be good for you to join AC and join in the Note 7 forum discussions. There's a lot you can gain from it.