We have 6 boxes around the house, using clumping litter in each, all of which are covered. We don't have problem one with flinging litter, but, since we use clumping we were having a tracking problem (all hardwood floors). So I found the squares of kennel mat, you know its got the interlocking sides with a grid pattern, and since the boxes are inside of closets we put the mat infront of the boxes all the way to the entrance and exits and viola! no more tracking problem.
I use an extremely deep-dish litter box with a cover, and even have a litter-collecting mat outside the little opening, yet Satey STILL tracks litter all over the place. He's even short-haired and I use the crystals which track less than half as much as any other litter I've ever used. I am convinced there is absolutely nothing I can do about it.
Snowball's litterbox is in a quiet corner at the end of a hall. He has always kicked out some litter no matter what we have tried to do. Now I just dustmop the floor around his litterbox daily, which prevents the litter from being tracked up the hall and into other parts of the house.