There’s a philosophy that every bat can only endure a finite number of impacts. Additionally, some of the higher-quality, more expensive bats may be more prone to damage when exposed to colder (off-season) weather. Some manufacturers go so far as to issue a disclaimer stating that higher-density baseballs may damage higher-end bats. While these would all seem to caution you against using your favorite bat in a batting cage, there are a few other factors to consider. A composite bat needs to endure roughly 200 impacts before it’s broken in and functioning at peak capacity, so a batting cage can be a benefit initially. When practicing your batting for technique and timing reasons, you want to simulate the live game experience as closely as possible, which requires using your favorite bat. In conclusion, the risk of damage increases with every impact on a bat, so it’s up to your discretion how much risk you’re willing to accept during a practice situation.