Yes, it's very common to wear half chaps over jeans, although they can be worn over any type of pants, including breeches or jodhpurs. Many western riders like to wear half chaps over jeans, and the idea is that they can be worn with any type of boot. Half chaps are made to fit over any type of boot, and that's why they're often used by horsemen. They're also commonly worn by riders of other western riding disciplines such as saddle bronc riding, bareback riding, and rodeo.