To see the effects of stitch length and density on fabric, I suggest creating a stitch swatch chart. Full instructions for creating a swatch chart similar to the one below in Generations digitizing software are included in Anatomy of a Design: How to Think Like a Digitizer and Become a Better Embroiderer.
Articles tagged with: Density
What is Density?
Density is the distance between individual stitches in a satin column or rows of stitches in a fill. The closer the rows are to each other, the more dense an area of stitches is.