I still think you're not quite understanding.

It sounds like Mottom parks her palace over one world and starts consuming it, but while it's there she goes and visits OTHER worlds every few days to show the flag and make them remember that yes, she still rules them. During those short visits she picks up maidens to feed the tree.

So she's consuming one world while simultaneously pulling maidens from dozens of others.
If i were not understanding something, then you would have hard evidence you could link to in the comic to support an alternate view, instead of speculations that are in no way better than my theories..