What are the common causes of joint compound cracking and how can it be prevented or fixed?

Common causes of joint compound cracking include improper application, excessive drying time, and temperature fluctuations. To prevent cracking, ensure proper application techniques, allow sufficient drying time between coats, and maintain consistent room temperature. If cracking occurs, it can be fixed by sanding down the affected area, applying additional joint compound, and feathering out the edges for a smooth finish.