With my small needle and tight stitches, I don't get thread bleed through. I am almost always piecing scraps together, various darks and lights and almost always use a light camel/beige and a light steely gray/blue threads for my top and bottom, these shades tend to blend in/disappear more than others. The two colors do help me see if I am having tension problems, but they are all the same brand of thread.
The only time I bother with thread matching is for the quilting thread, or for garment construction. Otherwise it's beige/grey set up in the machine.