We have a 16 yo hemi, she has never been a fan of litter. So we use potty pads cut in half on a grid litter pan. She also will only use each pad once.
When we travel over night, we also have auto litter that has very shallow litter with a potty pad underneath.
She will use both while we are gone for 1.5 days. Auto will scoop everything to one end, smooth out and repeat. She has no issues with using both while we are gone. Didn’t start using auto litter until she was 14.
We have tried using a twice a day sitter, she refuses to eat, with multiple different sitters, so auto is the only way. She is not a people person, and truly hates any other animals.
We have refrigerated auto food, which she uses only when we travel, what food she doesn’t eat in 2 hours, the lid closes to keep cold and fresh. Rotating every 8 hours, with 4 feedings. She eats twice a day.
So there is hope for older cats, but will warn, auto litter is like a new toy, ours jumped in and out for days to watch it move.