True but for those that don't....
What is great also is that there are several different programs. You can run all sorts of comparisons for different Null Points and what is the effect when you deviate from the prescribed overhang. It shows changes in distortion etc.
In a Lofgren A setup a deviation of .5mm in extra overhang length can give you an approximation of a Lofgren B setup. You can also see that shortening in some situations the overhang (accidentally) can be worse than going longer.
You are able to plot maximum and average distortion based on differing setups.
You are also able to compare the difference between 9 inch, 10 inch and longer tonearms to see the effect on distortion.