If a network runs out of power mid-way through an item movement (for example with no energy cells, like a subnet with a single quartz fibre, and a large stack size like a high tier gregtech conveyor), then the item movement will fail from the perspective of the network's storage, so the items won't be removed, but it will succeed from the perspective of the storage exposer, so you still get them out. This allows you to infinitely pull items out of a network by ensuring it will always run out of power mid-movement.