For commonly available ball screws with 12mm diameter/4mm pitch, you get over 9:1 mechanical advantage just from that
The mechanical advantage of a leadscrew is not a dimensionless quantity - its angle/distance, which
has units of rad/m (or arguably N/Nm). You can only say it has a 9:1 advantage over some other
leadscrew with 1/9th the value! There is no natural unitary leadscrew to compare to, as with
a gear system or lever.