It's funny.
I've heard so many people say;
"Dropped my phone with a screen protector on it, thank GOD! There was a huge scratch on the screen".
The reason there was a huge scratch (most likely) was because it was a SCREEN PROTECTOR. They're typically made from cheap plastic, and not made to withstand being scratched.
Apple iPhone glass is very durable. I keep mine in my pocket, without a screen protector. I've done so for a year and a half now. I've dropped my phone, dropped stuff on it. My son has thrown it. Not a scratch on the screen.
The only damage it's ever endured was a small chip on the right hand side. That was from falling at work, down 5 stairs, with my phone in my hand, and the phone dragging along a steel railing all of my 175 lbs on it while I fell down the stairs.
Other than that little chip.
Scratch free.