It does not matter as much as it used to - - -
When I first started piecing - which I do more of, than actual quilting -
I thought the piecing thread had to match the right side of the fabric as closely as possible. Not so much anymore. I won't use black on white - but I will use almost any medium with another medium color.
Matchy, matchy - after reading Jinny Beyer's book about color - "Color Confidence for Quilters" - I've learned that "bridging" the colors in the focus fabric is much more interesting than matching each color exactly.
Also - the overall "color" of a piece of fabric can look different from 15 feet away than it does ten inches away from my eyes.
The actual instructions may or may not be correct. I've learned that if they seem wrong - they probably are. So "authority" does not matter as much as it used to.
Matching intersections and pointy points are still important - but if after three tries, I'm still 1/8 of a inch off - I've learned to tolerate it. Not comfortable - but let's get this thing done!
What you think of what I think is important in the process - I am willing to listen - but -
How about you?