Whether you pp or piece with the templates or rotary cut, if you will take a few minutes at the beginning of each block and make sure you know which pieces are the "outside pieces and cut them a bit larger on the outside edge, you will end up with blocks that you can then trim (using your ruler) to the perfect size. Its MUCH easier than adding more because then you'll probably end up with that extra seam allowance right where you need to sew the blocks to the sashing...Just food for thought..