My experiences differ. After having my Schallers pop out on me fairly often (I move around a lot, and used to do so even more in my days of youthful exuberance), I switched to Dunlops and have had better luck. Not to say that my Dunlops have never come loose unexpectedly, but they've been better for me in that regard than my Schallers were.
Granted, if you just stand in place and don't move around a lot and always make sure that the receptacles on the strap have not moved/rotated, then the Schallers should be just fine.
Stand in place and don't move around? What's that?
Hopefully it will be a different story tomorrow...