Hi Marguerite
The SHX fonts are single line fonts, which are quicker to generate. I’m certainly no expert on these, but really just wanted to test the waters, with smaller sized fonts on some of my laser projects. From my tiny bit of research, it looks like they were perhaps originally used in AutoCAD, to save time in their computers (generating in their technical drawings), and in my opinion, they aren’t a necessity, but I’ve seen no ill effect in trying some of them out.
If you are wanting to dip your toes in the water, to see how they behave, I’d suggest looking at SHX Font Collection .
Best
Lee