I finally have my comparison picture. The one on the left is my first sand shading attempt. The one on the right shows my "more aggressive" shading.
The one on the right definitely has a few spots you could call "extra crispy." I knew that when I glued the pieces in. While I thought they were probably too dark, I remembered that in my first attempt, some of what I thought was too dark ended up looking pretty good. I don't think it worked out that way this time.
At the end, I think there are good spots and bad spots in both. Too bad I can't combine them.