system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What causes the testes to produce more sperm? How does the body know not to produce more when they are full?
gpt
So, a lot of guys have this idea that there is a finite amount of room in your testes and that your body can only produce a limited amount of sperm.

In truth, your body is almost always producing sperm. While yes there is a finite amount of room in your testes for sperm to be created, in practice it is near impossible to ever reach this cap. One, because your testes can expand slightly, vastly increasing sperm storage. Two, because the amount of sperm your body can actually store, even before the aformentioned enlargement, is a pretty crazily high amount. And three, because older sperm are usually broken down and 'remanufactured' into newer sperm.

Your body nornally (Outside of a few diseases/nutrient deficiencies) does a pretty remarkable job of breaking down old or improperly formed sperm, absorbing the remnants, and then creating new sperm.