Just and idle thought here. A quick search found nothing on this specifically. Perhaps it's been explained away quite readily, but... wouldn't the most foolproof and accurate anti-skate remedy simply be a calculated tilt of the entire turntable? Perhaps some form of chart would be available to determine the degree as a factor the stylus tracking weight? Just a thought.
One of the guy's who worked on the Platine Verdier' used to advocate that very thing. The problem is the angle is fixed so as the grooves narrow the arm speeds up and changes the thrust force against the groove sides. Spring loaded bias attempts to compensate for the change.
Do the grooves actually narrow, or does it result from the angle of "attack" of the outside of the groove becoming more acute toward the center? If so, I guess that would indicate a need for some progressive restraint. Can it be that measurably different from the outside to the inside groove? Has anyone measured this?
These inquiries would be answered in The Vinyll Engine forum. They are dedicated to Vinyll and have lots of tutorials and such that go into depth on each topic. I only mention it because they have been a great help to me on some of this stuff. To answer your question the grooves do narrow and the angle becomes more acute resulting in greater side thrust on the inside groove. The old issues of the Tracking Angle magazine had a 20 page white paper on bias settings for tonearms. I believe it is still available as a download on the net. Free of course. I know they took before and after electron microscope photos of the groove of a record to show the effects of this.
I don't think the grooves are narrower at any point on a record. Perhaps you mean that the diameter of the groove reduces as you get closer to the center. Why would the arm speed up?