Only if it's actually generating more thrust. It could also be generating less thrust. The problem is many people never go so far as to measure the thrust or speed. They put the prop on, get more RPMs and conclude that it's more efficient and therefore better. Then since they've already convinced themselves that the prop is better, they perceive that it's also better in the air, perhaps partly from hearing that the engine is turning faster. I accept that some people actually measure and conclude a particular prop works better for their plane/engine combination, but many just go by what they hear from others or conclude from the engine turning higher RPMs.