I also use the wood pellet litter, I used it in the open litter box and continued to use it when I got the covered box. It works really well so I haven`t had any reason to change to anything else.
I scoop the solid waste every day.... I don`t use the usual scoop for the solid waste, I use a ladle! Also, most days, I use the normal scoop to sift the pellets free of the sawdust, then scoop out the dust with the ladle and then add a little, or lot, as needed, of fresh litter.

Chris