Thats the thing, mine is just two of how many million. So as the old saying goes your miles may vary. I think she was just cursed with the 6S or all those drops finally caught up to her and the phone gods frowned upon her dropping those beloved 6S's lol..
Does not mirror my experience with the devices from 3S all the way to 5S. Those things got screen cracked quite easily in my experience. I never had one last more than 6 months before breaking.
The only device I have had that was impressive on drop performance was the Samsung Note 4. You literally had to try to destroy the thing.
My partners iphone 6 has lasted but then again, she had it in a case from day 1.