Couscous gets everywhere, no matter how hard you try to keep it contained.
It depends how much I am making. A pint or a quart. I typically only make one or two servings at a time. I mostly eat it on salad, or with cucumbers and tomatoes.
It cooks quickly, so I only add very hot or boiling water (if I am using boiling water, I ensure the jar is preheated to avoid cracking) to the jar and let the residual heat cook it.