I volunteered once to put a quilt top together that 20 different quilters contributed to. The blocks were suppose to be 12 1/2 inches (unfinished). They were anywhere from 11 1/4" square to about 15 " square (kinda of square). On the ones that were too large I just put my 12 1/2 inch square up ruler in the center and trimmed. The ones that were too small I wound up "framing" them with a neutral fabric. It was a pain. If one person works on the top, another on the backing and another binding and another quilting it would be more consistent. Also would move a whole lot faster.