Altering the litter every 4 months helps prevent buildup of odors and micro organism. It is actually an efficient way to keep up hygiene. The Pet Foodstuff Makers’ Affiliation (2020) advises that total changes lower the risk of urinary issues in cats, as fresh litter provides a healthier natural environment. https://www.petskyonline.com/search/?query=crystal%20silica%20litter