In All the Pretty Horses, have John Grady and Rawlins broken horses before? Do they seem knowledgeable about it?

Born and bred on Texas ranches, John Grady and Rawlins know just about all there is to know about horses.  Their prowess is tested in the first pages of Chapter 2, when they are presented with "as spooky a bunch of horses...as...ever (seen)" to break.  John Grady audaciously contends that they can break the whole string in four days, and they set out to accomplish this with an unorthodox combination of methods which include rope skill, hobbling techniques, talking to the horses, and patience.  Not only have the boys obviously broken horses before, but they probably have done it together - they work together like clockwork.  When it becomes apparent that they will succeed in their brash boast, a large crowd of local people turn out to watch.