Past 90 micron, the incidence of broken trichomes and non-capitate stalks increases, so the quality can begin to decrease, consider it a point of diminishing returns; your total mass of concentrate increases, but overall quality decreases. 25 micron is generally recognized as trash and used for cooking or topicals.
Pretty sure that our own reincarnation of Frenchy Cannoli can fill in some blanks:
You’ll find microscopy, and a full explanation of his process here