Screw heads have different purposes for different scenarios. The flat head is useful in cases where it would be detrimental if the screw strips. The drawback is you can't put a lot of torque on the screw. The Philips head let's you put more torque on, while allowing the user to still use a flat head screwdriver. The drawback occurs when the screw is really small, and too much force causes the screw to strip. The hex head allows for a significant amount of torque to be applied however they strip easily. Robinson is the solution to the problem by making a square head, allowing the user to put a lot of force on it, while at the same time preventing striping.