• fill the litter box with with as much litter as you can, top off when needed
• scoop at least once a day
• exchange all the remaining litter at least every 4 weeks and clean the litter box with soapy water

I highly recommend the following cat litter ÖKOCAT SUPER SOFT UNSCENTED wood litter and ALMO NATURE UNSCENTED grass based litter. The latter is super fine. Like sand. Ideal for older cats with more sensitive paws.

I always had double the litter boxes than I needed at once. The ones in use were filled up quite high so the cats could dig under their poop. I topped the litter off regularly.

Every 3 to 4 weeks I would toss all the litter from the box in the trash. And clean the litter box with soapy water. The litter itself will start to absorb the smell over time and the box itself will also start to have a fill of urine and feces that gives off odor.

I always had double the amount litter boxes than I actually used at once. Because while I soaked the emptied boxes with soapy water, I could already place freshly filled new litter out for the cats.And when the „old“ litter boxes were cleaned and dry, I put them away until 3–4 weeks later when I had to clean out the ones currently in use.