Kitty's WonderBox Disposable Litter Box

I have two indoor cats and have been looking for something - ANYTHING - to lessen litterbox odor. After reading other reviews of this product, I thought I'd give it a try. First, I ordered the 3-pack, which seemed like a great deal, but then shipping doubled the price, so there went the great price. Then I got the order (pretty quickly), but there was only one WonderBox, instead of the 3-pack I ordered. So I called the company directly and they sent me a 3-pack and allowed me to keep the single box I already had. So I ended up getting 4 for the price of 3, but still, when shipping is added in, you're still not getting a very good deal. I have two litterboxes which are cleaned every other day. I left the WonderBoxes in my normal plastic covered litterboxes for a month and by the end of the month, there was cat urine all over the place, seeping through the WonderBoxes and was VERY STINKY and super gross to change because the boxes were dripping urine. The odor was controlled for the first few weeks, so I think that a full month is just too long to go between changes. If it weren't for the shipping doubling the price of these boxes, I'd continue to use them, but when that darn shipping is added, it makes the price for these boxes not worth the smell-control they offer, especially given how frequently they need to be changed (once over 2-3 weeks).