I always check seam allowance the first few times I sew with a new fabric. As previously mentioned, you actually check the size of the block since being off even 1/16 of an inch if you are working on a large quilt can really mess up the measurement. The leader is just trying to make sure the quilt pieces all fit together. Basically (as others have said) make sure your blocks are exactly the size the directions say and use whatever seam you need to make sure you get it. If you are concerned about issues with a smaller seam, use a smaller stitch (I use 1.8).