Kitty Litter Works Better for Some Cats Than Others

[piano cat]

I have multiple cats. I find the clumping kitty litter works better for some than for others. Have tried different litters. It particularly does not work well for the mother cat and her two female offspring, youngest now 9 years old. They have four boxes. Another unrelated female, one year old, is fine. The boys are fine. I do note the girlies like to pee in one box and poop in another so maybe it's just too concentrated, but still - anyone else notice this?

 

[IndyJones]

Older cats do pee more and I think the litter just doesn't clump as well with such a large amount or if they go in exactly the same spot without buring like my cats do.