Finn is our 5 month old, and he's recently picked up the nasty habit of flinging as much litter as he can out of the box! Doesn't matter if it's a newly cleaned box or not, he will scratch and kick and fling. He is an excellent box user otherwise, but he does like to go in there just to scratch at times.
I contemplated getting a covered box to help keep it contained, but I've heard mixed signals about using them. I use a paper pellet litter (thank goodness, much easier to clean up than clay), and I do use a litter box liner to make it easier to clean. I'd love to not have to constantly sweep and vaccuum to keep the litter out from underfoot.