I've always treated accuracy as a goal but precision is a must. If you cut 4 pieces of wood all the same length and miter all the corners so the angles total 90dg at the corner and 360dg for the entire square -- it will be square.
If the table legs are 27.75 inches or 27.57 inches, it doesn't normally matter as long as "ALL" of them are the same. I strive for ok accuracy --- but always for repetable precision. For me it's story sticks and blocks. Measure the first one close, make all the rest the same.
Mike-in-Michigan (Richland that is) <br> "We never lack opportunity, the trouble is many don't recognize an opportunity when they see it, mostly because it usually comes dressed in work clothes...."