Whenever I do a pattern for the first time, I follow the directions exactly. So do a practice block. But, I agree, that the reason is probably to reduce bulk.
If you are worried about the seams, backstitch at the beginning and ending of each seam so your stitches stay tight. I saw Fons and Porter the other day where Maryanne and Mary were demonstrating how to begin sewing two to three stitches, then turning the piece around to do the seam, then ending it the same way by turning the piece around and stitching two to three stitches. It keeps the stitches tight on the end.
(They were demonstrating on a Babylock. When in quilting mode, Babylocks don't back stitch but stitch in place. You have to switch to sewing mode and then it will backstitch. So, I guess it was just easier for them to turn the fabric around.)