Having 3 cats, this is something Im savvy about.

what PP said, about upending it every 3 or so days? Totally agree.

Yes, you can scoop it, but even though you do that it still keeps tiny bits of waste in the clay, and thats enough sometimes to cause a stink. Personally i scoop the big stuff daily, and replace entirely every few days. More expensive but your house doesnt stink and your cat doesnt pee everywhere because its cranky at the litter.

However, it depends on your kitty. Some kitties are extreme OCD types who need it spotless or they wont use it. Some kitties could care less and will go for weeks on the same box. But generally thats what I do.

Also, if you have multi-level house? Put a litter upstairs and one downstairs.

Plain clay is fine - just be aware that it will track around the house some - you can either put a towel down in front of it, which will help pick the stuff out of kitty toes, or you can get a special mat that does the same. Personally Id just go with the towel.

With other types of litter it is trial and error. Clay seems to be the most widely accepted, however some cats will use other types, and some will outright reject it if its not clay. Whatever you choose, despite the temptation stay away away away from scented. Ive had 3 cats in my life get urinary problems due to the scented clay, one of which also broke out to the point where he had to be kept at the vets and given steroids. Think of it this way - if you had a newborn, would you put perfume on it thats based in oils that can harm skin?