If you look carefully, you can see the difference in scales. The dark blue in the center is done in a 1.4 mm wide and 1.4 mm long stitch. The light blue behind the dark blue is 2,0 mm x 2.0 mm blanket-stitch, my usual size. The pale lavender dots are 1.8 mm by 1.8 mm blanket-stitch. I was a little nervous to do the dark purple curves because I decided to stitch them in a 2.2 mm by 2.2 mm blanket stitch. It was really fast to stitch because the stitches were so long, however it did come with it's challenges. Going 2.2 mm into the fabric meant that when I got to the points the stitch would've gone beyond the fabric and over onto the background. I angled the stitches in a little more to make sure they stayed on the purple fabric and it worked like a charm, but I had to remember to do that at each point.
Overall, I am very happy with the different sizes of stitch. I think it adds a little more interest to the block and I want to play more with vary sizes of stitch.