Setting VTF by ear is indeed the way to go. A scale is a tool used to get in the ballpark or to return to a known baseline after changing cartridges. It can't determine the final value that's optimal for a given cartridge on a given day.
What you may find interesting is that anti-skate should ALSO be set by ear. Depending on the arm and cartridge, you may find a far lower level than expected is optimal. When you're feeling experimental some day try this:
1. Reduce AS to a very low setting, close to zero if possible.
2. Play a very dynamic record, listening for R channel mistracking.
3. Increase AS in tiny increments until you can just barely play the tough passages cleanly.
4. Note this AS setting. Now A/B some familiar music at this (possibly lower) setting and your original (possibly higher) setting. You may find the lower setting gives you clearer imaging, better microdynamics and clearer HF detail.
It's worth the experiment. If your rig and system are resolving enough you'll hear the differences and learn something new about AS.