Allow me to be the example. my friend was putting his cell down, to pick up mine to look at it. Mine was sitting face up on the desk. he dropped his as he went to pick up mine, and the edge of his phone, caught the edge of mine, not more than a 2 inch drop. Shattered the glass on my s4. Now I wish I had a screen protector on.
Would of it stopped it? Cant be sure.....but...ill never know.