As the title states, this is a generalized guide. It is based on traditional best practices for handwork. Some of the sizes here may be difficult to find sources for. Thread comes from worldwide sources and varies in size. Different awl widths are notoriously difficult to find. Style variation will have a big effect on some of these sizing choices. At the time of this writing large stitches with wide flat braided threads are in vogue. This guide is still useful. If you proceed by choosing your stitches per inch length first, rather than the leather thickness.