When using the 'snubbing' braking technique to control speed down a long, steep grade, how should the brakes be applied?

1. Apply light, steady pressure all the way down the hill
2. Apply the brakes firmly for a few seconds to reduce speed to 10 km/h below your safe speed, then release them completely and repeat when speed rises
3. Pump the brakes as fast as possible
4. Apply brakes only when the vehicle reaches the maximum engine RPM