Three times I think? Maybe four? Once quite forcefully: my wife has a hatchback and I couldn’t see well at night into the back of it, so I put on the flashlight of my new iPhone 6 and wedged it where the hatch meets the roof of the car. Of course, I forgot about it and tried to slam the thing shut three times before it dawned on me what had occurred. Oops.
The other times, I don’t remember. They were only like $100 fixes so I didn’t much care. All had an enclosure of some sort. It seems that when the phone falls perfectly flat onto the ground that it has the highest chance of cracking for me.