The frequency of brake pad replacement varies depending on several factors, including driving habits, vehicle type, and brake pad material. Generally, brake pads should be inspected regularly, and replacement is typically recommended when the brake pad thickness reaches a certain minimum level, usually around 2-3 millimeters.

In general, it is recommended to have the brake pads inspected by a qualified mechanic during regular maintenance intervals or whenever you notice signs of brake wear or decreased braking performance. Some common signs that indicate the need for brake pad replacement include screeching or squealing noises when braking, a longer braking distance, or a pulsating brake pedal.

It's important to note that this information is provided as a general guideline, and it's always best to consult your vehicle's owner's manual or a certified mechanic for specific recommendations based on your vehicle's make, model, and driving conditions.