Re: litter boxes...
Eh, for the jumbo litterbox I lift one end and shake so all the litter piles at one end. Then I run the scoop through, taking little 'bites' of litter and sift it at the 'clean' end, dropping waste in my kitty waste-bin. When I've worked my way completely to the end, I use the scoop to evenly distribute the litter.
With the litterchest (2'x2'x4'), I work it in a similar fashion; I use the scoop to push all litter/waste away from one end and as I sift through the litter, I pile the 'clean/sifted' litter at the cleared end. When I reach the other end of the box I then smoothly distribute the litter through the whole chest.
For me, working the litter in this manner allows me to clean the box/chest completely and reach and remove waste clumps from all sides and the bottom.