You always have to adjust for pad wear with a mechanical brake regardless of whether the second side moves or not. If you only use the cable adjuster, you end up with a really dead-feeling brake.
So with dual action you'd have to undo the bolt tighten the cable redo the bolt. Whereas dual action would require me to also adjust the non-actuated pad with the bolt on the side? I've only briefly used mechanical disk brakes but never got on with them, this might be what I've been doing wrong.
The trade off would be having to adjust for pad wear?