Bio balls, lava rock, ceramic rings, Scrubbies, all do the same thing, they are surfaces for beneficial bio film bacteria to live on.
That population of bacteria will equalize and coincide with the amount of ammonia and nitrite produced by you fish ever time. If you have a sufficient amount of media to hold bio film for your stocking level, that bacterial population will not grow higher because you add more, it falls or rises with available food produced by your fish population.
Replacing it with new media does nothing, except maybe causes an ammonia spike because you've removed a large population of beneficial bacteria if you remove old bio media.
Mechanical media can be replaced as it falls apart.
I rinse mechanical media such as matting, or filter socks until they fall apart and become useless, but not before,
I would only replace bio media if a serious disease ravaged the tank it serviced..