I am currently working on my first burlap cross stitch project. I tried to use two strands out of a six strand skein like I would have used with 14 or 18 count Aida cloth and started over after about 80 stitches. Two strands do not show up well on the burlap. I tried using three strands the next time and they show up very well. I am very pleased with the results from using three strands of floss.
Have a nice day!