As PaperPieces stated, the finish is the important part. Using a scant 1/4" seam allows for the thread and fold so your block/ item turns out the size its supposed to be. Especially important with blocks/quilts that have many, many seams ( like bargello). With a pattern like a bargello having even an extra 16 th of an inch adds ( subtracts) a whole inch in finished size in 16 strips/seams. Those little bits add up.