To me, the one rule that is supreme is the 1/4" seam allowance. Most all quilt patterns call for the 1/4" seam allowance, and I like my blocks to fit together, so I am very vigilant about this one -- especially in a quilt that uses more than one block pattern, like a sampler. If you are quilting with only one style of block, by all means fudge on the seam allowance, they'll all turn out the same size, and it will be great. I am one of those "pointy" quilters, as Kaye Wood calls us, and to me there is nothing more satisfying than to have all my points pointy, and my seams straight. I know I am a little OCD about this, but I have found that quilting is a happy place for my Obsessive-Compulsiveness.