As every material has "0"(Zero) twist point, this is the desired end point for furling. It is perhaps defined best by stating that it is that point for a specific material beyond which further twisting will NOT occur, under proper tension (weight). If it is not under adequate tension, it will begin to pig tail. For a furled leader, it will be that point at which it will break before either pig tailing or twisting further. This will be that point with the tightest twist possible for the material.
Using the info Karel mentions will be a big help in determining (calculating) what the appropriate weight is for any given material. Once it has been calculated, then it is a matter of doing an actual test, using that material and weight, to confirm the calculation.
aged sage