I have noticed that some Japanese rope is constructed with each ply being is made up of a number of single equal diameter yarn, e.g. 8 in a 6mm 3-ply, twisted around a central one, a bit like a wire cable. I am more used to seeing all the yarn twisted together or the use of double twisted yarn.
Is this typical? What advantages/disadvantages does this have? Does it require complex machinery? I can envisage how it could easily be done by hand. Any thoughts?