Yes, I'm a witness to this. Since shinies aren't random, I don't know how this really works, but the shiny patches are guaranteed shinies. I suppose, additionally, normal and blinger patches have the 1/8192 chance of a shiny. How it works, I don't know.
I found a Roselia that way, and my sister found a Staravia and something more recent...Wobbuffet? It does happen. Leave no patch unchecked!