How a brake pad wears is influenced by the rest of the system. Hardware, hydraulics and slides have more influence over how a pad will wear than the driver or friction material. Being able to read the patterns is critical in inspecting and diagnosing problems.
Cardone Industries is one of the oldest remanufacturers of brake calipers in the world. They have made a handy chart to help you identify certain wear patterns and what should be replaced to restore the vehicle to optimal condition.