It is essential to take into consideration the cat's natural instincts when providing a toileting area for kitty. For example, it is instinctual for a cat to seek out a clean, easily-raked substrate in which to eliminate.
Cats also prefer to urinate and defecate in different areas.
Consequently, you should have one litterbox per cat in the household, plus one. Many products sold in stores for cats are not suitable for cats because they do not satisfy the cat's natural instincts. Hooded litterboxes are a perfect example. While some cats will use them, they defy the natural instinct of the cat to find a place to eliminate which has escape potential. If the cat is the slightest bit uneasy about its territory or about the people or animals who share its home, it will be reluctant to enter a box in which there is only one way out and in which it could be easily trapped.