I agree, Bear. Lots of things that used to seem to important to me, now aren't.
I used gray, taupe, off white or whatever for piecing. I recently found some off white aurifil on sale so that will probably be my piecing thread.
In my younger days, I used to "match" fabric by standing on the table and pulling fabrics from the boxes on shelves on the wall and dropping it on the table or floor. I found that fabrics look different from even 5' away. Since that's how most people see things, it works well. Now I also use my camera to see things from far away.
I'm also don't feel that following instructions is that important. I learned when I did a lot of garments that there are often better ways to accomplish the same thing than the instructions. But then, as I've gotten older, I've found that I feel much freer to do things my way than the "right" way.
As far as matching intersections and points, I'm good with being close. Exact doesn't always matter, but the intersections have to be close. I don't like points getting cut off, but have ignored a tiny bit on occasion.