This one may be a mistake. Bulky yarns are sometimes unflattering to the non-willowy among us, and the exaggerated slubs may end up looking as if a swarm of caterpillars are marching across my back.
There must be an algorithm to spin in the alternating colours and space out the slubs so that it doesn’t repeat at the same point in each row, whatever the row length. I tried to work it out in a primitive way.
Not an infallible algorithm, obviously.