If your quilt is made up of the same block repeated, it isn't as important for them to come out a required measurement. The blocks do have to be all the same size however for a good result. If your block is slightly under and all the rest of the blocks are the SAME, just adjust your borders to the new size. In the case of different blocks you do need a constitant 1/4 inch seam or scant 1/4 inch seam to end up with blocks that will fit together well.