All phases of the construction process are important when sewing the units of the block and it is important to know the kinds of places you have a tendency to deviate from true size seams-like at the end of a seam. Most blocks call for pressing to one side and nesting. You still need pins to get perfect seams. You spoke of stitching rows together. It is especially important to be sure that every junction matches before you sew. If they don't fit 'comfortably' it is best to go back and fix the problem. If you force it to fit it will show on the front and you can't always quilt it away. Starch and washable glue are great tools but they can't substitute for accurate sewing. I do think open seams are more of a challenge and hand basting small areas works well. It takes more time but saves lots of frustration and unsewing.