Not sure. I rarely fall when climbing rocks, so I’m not a total butterfingers. I often take out my phone to use as a flashlight, angle mirror etc and leave it balanced precarious places. Never had a phone break in probably hundreds of ground falls (always using a case). Since it’s never broken, I don’t expend effort to prevent it from falling.

Edit: sibling comment is correct, sketchy pockets of athletic shorts are a major offender. Actually it bothers me way more when my car keys fall out of those.