Stylus Force Guages - why extreme accuracy?

I am under the impression that, when setting up a phono cartridge, one sets the tracking force to the manufacturers recommended force, and then dial-in the final force by ear. If that is the case, then why are extremely accurate electronic stylus pressure gauges popular when the force is most likely going to change during final adjustment by ear? The Sure SFG-2, costing $25, has worked great for me to ball-park the initial tracking force before final tweaking. So, what benefit is the Winds ALM-01, costing $800, going to provide? Is it important to set the initial force to within a tenth of a gram, when that will change during final tweaking? What is the procedure those of you who own expensive gauges use for final adjustment by ear?