@Reze yes, if a string makes more knots, it will be used more and it needs to be longer. Making knots uses up more string than not making knots. Simple as that.
@Alexaa_k that depends on how fast you knot in general and how good you are at segment knotting. It's only 12 strings and easy to segment knot, so it should not take super long.
c_j_m
