Same with me on all of those and including back to the 3G. I use the Apple Silicone case when I'm running or at the gym, but I take it off as soon as I'm done. I've tried a variety of cases, but I wind up returning most because I hate them on the device. All of my phones looked terrific when I sold them.Yes, no case here. Just like my X, 7 Plus, 6S Plus and 6 before it. Haven't shattered a screen yet. And worst case I have apple care+ and have to pay the $99 deductible. I'll consider that a "no case fee" if that ever happens.
What I’ve gathered as long as the glass isn’t cracked, it’s acceptable. First time doing iUP and would like to go case less. Might end of doing that since I have AC+.I think where this matters is in resale value. If you dont resell or are on the IUP then case-less seems appropriate. I would sure like to know under IUP how much wear and tear is too much from Apple's perspective.