I prefer having a clean fresh litter box for my cats.
Simply put, I shake down the sawdust whenever I see it;
solids are scooped into the water closet.
Once a day I separate the sawdust from the pellets.
The bottom sift sheet makes it easy to separate them.
Maintain the depth at about 1.5 to 2 inches.
I sprinkle the sawdust on the ground or use it as garden mulch,
in accordance with the rules of nature. That makes
the grass and plants happy.
Cats do not like change. They are ultraconservatives,
way to the right of right wing extremists. Therefor,
do not suddenly change the type of litter. At the start of the changeover,
the box should have a one-inch layer
of pine pellets covered by at least a 3 inch layer of their accustomed litter.
As they use it, they will stir it up themselves. Over a two week period,
each time you change the litter,
thin down the top layer until you are just using pine pellets.
They will show their appreciation by continuing to use the
box. You will be in Cat Box Heaven.
However, for a regular cat box, the manufacturer recommends
just shaking down the sawdust. After a week or two,
when most of the pellets have converted, replace
the batch. Maintain the depth at about one inch.