How many drops does it take to damage iPhone 4S?

Recently I changed my phone from iPhone 3GS to 4S. My 3GS has encountered lots of dropping onto the ground, causing the Power Button unusable, Home Button not functioning well (had to press hard), and the Mute Switch which when switched to Mute state, the phone was changing to Unmute and Mute and repeating itself. The operation almost relied heavily to Assisstive Touch.

Now I got this 4S recently, my dropped few minutes ago (I think it's a light drop) and of course, the phone is fine. I have this "protective" case on, but the sides aren't rubber. So I wonder how many drops to the ground does it take to start damaging the phone?

It only takes one. But it all depens on how far it fell, if it has a case, and how it hits. This is like the ole' how many licks does it take to get to the center of the tootsie pop… There's no real answer. Just stop dropping your phone… At a minimum, its going to cost you $100 to fix a broken screen, or about $500 to replace the phone… Its not some cheap toy, you are basically carrying around a TV in your pocket… If you treat your device like an expensive accessory, it will last a LOT longer. I haven't had a case on my phone for the past 4 years and never once dropped it or scratched it.