How Often Should Shower Caulk Be Replaced?
You should replace shower caulk yearly to be sure that you do not have any issues. The caulk is there to protect water from getting behind the hardware and the sides, which can cause damage to the walls and develop harmful mold. It is possible to get a small hairline crack in the caulk without realizing it, and this will allow the growth of the harmful mold and cause damage.
Another reason to re-caulk yearly is that by the time you notice the black mold on the caulk, it has actually formed on the surface below and grown through the caulk.