I wanted to give my boots some sole. I needed a loop-cut around the lower section. However, I had so little geometry that the face on the side of the boot had 6 sides. The loop cut tool wouldn’t work so I cheated and used the knife tool to make the side of the boot into two quads, then the loop cut tool worked fine. I hope I don’t get booted.
It seems, to make it easier for Blender’s tools to work it may be necessary to leave some geometry just to have selectable loops. And then later dissolve all the edges that are of no use. A little like keying an animation and cleaning up later.