Yes @RoyalChick she might feel it’s safer. Also, the roost is a line formation, whereas the box is a flat space that allows different snuggle configurations. Just surmising that the line forces one or more to be at the “end” where they will be vulnerable to the other Bigs and further away from Mama.When she decides it's time to roost. And she may return to it for a bit longer after that for some reason only discernable to her.
My perspective isn’t traditional though, as my experience is solely with the Omlet roosting platform.