Slip-N-Slide Install

So,  I'm thinking maybe Syren had this issue, but I'm on the delivering end.    I did a great pinchbraid install on a girl, maybe 110 braids, all tiny really good looking, seemingly tight.  I was bragging that it was my best install ever. 

      So, anyway,  she has this super healthy strong straight asian style hair.  Thirty or more of those strands slid out in less than a week.  I just don't know.   She brought me a braid to see how it slipped out and the suckers were still tight... just not attached to her hair.

     I just can't figure it out.  It was a friendship install, so there are no hard feelings, but I'm reeling from feelings of incompetency and confusion.  It occurs to me that perhaps I shouldn't install on people with super healthy hair.  Any thoughts?

When I used to do my own modified version of pinchbraids, I used to take a regular needle and thread and sew a few times through the little braid after I was done and I never had any slip out. I'm not professionally trained by any means, but perhaps for slippery hair, after you're done with the pinchbraid you could put a needle on the thread thats attached and sew it through the actual braid part a couple times.

As I say though, I'm not at all a professional so maybe thats something thats already done when you do pro-pinchbraids or maybe it's not such a great idea! Figured I would just throw it out there because it always worked for me :)