The elliptical /bi radial tip was introduced first, to deal with "pinch effect" and other tracking/ tracing problems, then came the discreet quadraphonic disc recording process and everything changed for the better for more accurate groove tracing.When it comes to the heads used to cut grooves in the master, did their shapes evolve as "reading" stylus cuts were evolving? Assuming that the system of vinyl playback was originally engineered with particular parameters, it would seem logical that cutting head shapes and stylus tip shapes would have been engineered/spec'd together to produce predictable results. Did cutting head shapes change over time then to accommodate changes made on the playback technology side?
https://en.m.wikipedia.org/wiki/Compatible_Discrete_4