Roulette balls are typically replaced regularly, though the exact frequency can vary depending on factors such as the material of the ball, the amount of use, and casino practices. In general, a casino will replace the ball when it shows signs of wear or damage, such as becoming scratched or losing its smoothness. This ensures the ball performs consistently and fairly, maintaining the integrity of the game. Some casinos may replace the ball once every few months, while others might do it more frequently, depending on usage.