I agree with kwhite. When I took my first quilting class many years ago this was what I was taught. By not stitching into the seams (any of them) they are able to go any direction when the block is completed and pressed. It is also possible to fan the seams in a spiral fashion when doing 8-pointed stars and such.
Also, I knot my thread and back stitch at the start of a seam, when I come to a seam intersection, I back stitch on both sides for re-enforcement. At the end of the seam I knot and back stitch again. I do leave thread tails since it is the back of the piece.
Good luck with your endeavors.