I use these tethers if I feel the GoPro can fall off, but I've never had issues with my mounts. I usually get Smatree GoPro mounts for my Hero 3+. They are cheap and work well.
https://www.amazon.com/XCSOURCE-Tethers-Insurance-Sticker-Mounting/dp/B00JFS1TC6/ref=sr_1_2?s=electronics&ie=UTF8&qid=1498846263&sr=1-2&keywords=gopro+tether