Maybe this is pedantic but it does look like it has fivefold rotational symmetry, which makes it a lot more regular than a typical car body, for example. Still, complex geometry.
Yeah, it was probably something symmetrical in the laws that allowed them to simulate only single part of the coil - saving the computing time and lowering the search space, stacking up resulted in full coil.
I'm not sure about the laws you refer to. It seems to me that the constraint is that for a twisting ribbon-like plasma they had to have an integral number of twists or half twists in a complete circuit, not twisting too sharply, not too gradually.
