It depends. Depending on the age of the person and the fragility of the bones. It's not a "requirement" in any sense, more "if it's not a risk, you're not going deep enough" - typical standards call for 1/3 to 1/2 the chest depth.
As often as that - it's much more (almost guaranteed) that you'll tear the cartilage between the ribs at the front.
As often as that - it's much more (almost guaranteed) that you'll tear the cartilage between the ribs at the front.