Nonetheless, being a practical person, I think the hypothetical 3-D MLT design isn't.
I definitely think it would work. I'm less convinced that there would be a benefit over more conventional designs.
If lautering speed is the concern, I think all the same concerns that apply to fly sparging would also apply to batch sparging. The absolute best design is probably a false bottom, since you would effectively be able to drain the entire area of the mash simultaneously. And you'd want the shallowest grain bed possible.
As a practical consideration, I have a lautering system that's optimized for fly sparging. (A slotted CPVC manifold.
) Using a March pump, I average about eight minutes from starting the runoff to filling the kettle. That probably means each ~3.5 gal runoff takes about two minutes. I don't see any reason to experiment with other designs.