Charlie pretty much always neatly covers his poop. Except when he leaves his butt hanging outside the box. Usually he faces outside the box – often with the front half of his body outside the box. But he generally spends time carefully burying his poop.
Zoe, on the other hand, leaves her poop on top of the litter. Then she rushes in to wherever I am with a wide eyed look of horror on her face.
“Do you smell that?” She demands. “Somebody needs to do something about that!”
Overall, I think it best that everybody deal with their own poop.