How much weight capacity should a TV mount have over my TV's actual weight?

Mainstream reviewers and r/hometheater regulars generally suggest at least a 2x safety margin over the TV's panel weight, and more if the mount is full-motion and fully extended. A 65" OLED at ~50 lbs is comfortable on a 120-lb-rated mount; pushing a mount near its stated max is where reviewers report sag and arm droop over time.