You have just descended a long, steep grade and your brakes are very hot. You need to park the vehicle for a few minutes. What should you do?

49 CFR 383.111(b)(7)(iv) – Parking brake; AAMVA CDL Manual, Section 5, subsection 5.4.8 (p. 5-9)

Setting a parking brake on brakes that are still hot from a downgrade can damage them, leaving you with weaker brakes for the rest of your trip. Chocking the wheels instead is a simple habit that protects the brakes you just relied on to get you down the mountain safely.