I found that Danish Knot Stitch is easy to work, and fast. A thicker thread with a good twist, e.g. DMC Pearl 8, is easier to work and gives a better look, than stranded floss.
Here I used Danish Knot Stitch for a small Christmas ornament. Some stitches are worked in thin metallic thread. Hm, OK for an experiment, but the stitches with pearl thread show off better. The length of the 'legs' and the tension will determine the shape of the knot. You can get a knotty Fly Stitch or a fat triangle.
Do go and check out how Chitra has 'twisted and turned' the Danish Knot Stitch. She in a great inventor of stitch variations.