Stupid question: Assume I have anchors rated at 20lbs. I put up a shelf using 4 anchors. The shelf weighs 10lbs. Should I assume that the shelf can hold 70lbs o

Stupid question: Assume I have anchors rated at 20lbs. I put up a shelf using 4 anchors. The shelf weighs 10lbs. Should I assume that the shelf can hold 70lbs of evenly distributed weight?