Twisted coils are a great way of getting the low resistances required for high wattages on an unregulated device, while keeping the mass to surface area ratio high.
Two strands of wire twisted is electrically the same as two parallel strands of wire (side by side). When you add a second piece of wire in parallel, the resistance halves.
eg.
One 40mm length of 26 guage kanthal will be 0.45 ohms
Two 40 mm lengths of the same wire in parallel will be 0.225 ohms
Why is using multiple strands of thinner wire better than using a single strand of thicker wire?
If you have two lengths of wire with one twice the thickness of the other, the thicker wire will have
twice the surface area but
four times the mass.
On an unregulated device maximizing surface area and minimizing the total mass (amount of metal) is key.