Hear we go again.....a cartridge is designed with the suspension, magnets, coils, et al being in a specific place for all to for these disparate parts to work at their best places and values to do their best work. There is one and only one vtf that brings all of this together... The cartridge designed will give a range saying that no damage to the cartridge will result, or that there will be some tracking of the record at these extremes, however, the cartridge works best at the designers published optimal vtf. I am a pro musician, and have always sought to apply standards to all I have/do. I don't play Mozart in the style of Mahler, and don't track a cartridge at some quasi optimal vtf.