The Physical Limits in Shadesmar

I would imagine that the physical limit is simply there needs to be a lot of investiture all in one place. And then I also imagine that the location in shadesmar would matter. Because from Yasna, the little bit that we know about traveling through shadesmar as an else collar is that it's very difficult. She wants to move an army from point A to B. It becomes more difficult if she is trying to make this big transition across the cosmere.