Basically I will see if it develops any wear from normal use, sliding in and out of my pocket, etc. If I see anything after a few days then I'll get a screen protector. Otherwise, I won't bother. I didn't use a screen protector on my OG and it lasted me about 2 years with practically no blemishes on the screen or, for that matter, on any part of the phone. Screen protectors/cases exist to make money off of clumsy people, or people who don't know any better than to say no to the myriad of accesories the Best Buy employee tries to talk you in to.