I think the point is, this is fabric -- a soft medium, not stone or wood or metal, which do not have any "give". There will always be discrepancies in blocks, sections, segments because of this give. One can make minute adjustments to accommodate this give, or learn to accept the properties of the medium of their choice and "not sweat the small stuff".
That said, my piecing is accurate, a bit meticulous, well pressed, and then I do not sweat the small stuff! But, I've been doing it for 30 years; practice makes "better" in this medium.
Jan in VA