All metal SS lock nuts

I have had issues with my md180 nuts loosening almost since day one.  I finally just put a 2nd regular nut on top of the nyloc nut, and put 2 7/16 wrenches and some spare nuts in the hatch.  I have never had issues since double nutting all of the cables. 

I have had issues with my md180 nuts loosening almost since day one.  I finally just put a 2nd regular nut on top of the nyloc nut, and put 2 7/16 wrenches and some spare nuts in the hatch.  I have never had issues since double nutting all of the cables.

that is what I am doing, carrying 2 small 7/16 spanners, 2 new nylock nuts, and 2 regular nuts.

What's the QA/QC mantra? Anything more than 3 is,a trend? Might be time to tell the maker there may be an issue.