Yes you will need more than one bowling ball. Every bowling ball has there limits or one bowling ball can only do so much. Some bowling ball are good for heavy oil, some are good for medium oil and some bowling ball for low or dry lanes.
So if you are using a heavy oil ball, over time you have to move left or right due to the oil is going away or the lane is getting drier. Different bowling balls do different things just having one bowling ball is not going to cut it. Your one bowling ball may not work well on the lanes so this is wen to switch to another bowling ball and try that out.
Even in bowling leagues, in warm ups before leagues bowling I will try out 2 different bowling balls to see how is the oil and how to bowl will react on the lane. My stronger bowling ball may not work as well but my weaker ball may work better. All bowling lanes are different so you need more than one bowling ball.