it also depends on how much metal you want to lose.
if you are cutting fine parts in delicate areas , jewelers saw is king.
if i am cutting a mech in half , where i probably know i am going to re sculpt part of the area i cut through i will use the hobby saw just for saving time sake and not breaking too many jewelers blades .
Caz on here only uses a jewelers saw for everything, and takes his time making a cut, but he has this great thing called patience........