As mentioned, the cold flow of the PCB is a killer, but it is worse than that. If you just screw the terminal to the board, and the PCB will prevent the correct torque being applied then the joint will get warm. At 120 deg C the PCB passes its glass transition temperature when it becomes like a stiff paste. This will not help the long term reliability of the joint.
If you screw terminals to a PCB always use Belville washers. Flat, crinkle and all types of shakeproof washers are a waste of time.
How do I know? Repairing and scrapping all types of electronics.