That single bolt system has been a PITA since it was introduced. It's asinine that bike manufacturers are still using it.
The Felt TK1/FRD does use a 1-bolt system, but it's indexed with grooves. You have to remove the guts to rotate them 1 degree. It's the best implementation of this type. But, as Clythio mentions, the 2-bolt system that's been in use for decades (think Thomson) is simple and effective.
EDIT: Earlier versions of the TK1 system did use the style that is prone to slip which I assume is why they improved it. I recall a US National team member telling me about his saddle tilting on him using that frame.
Last edited by carleton; 12-16-19 at 01:27 PM.