After my GSD, Becca, passed on 8-31-18, I took a look online at shelters in my area of CA. I didn't see any GSD's at that point in time. There may have been some after all the CA fires, but I already purchased a puppy from a breeder at that point. I think that rescues that focus on a certain breed, tend to scoop up a particular breed from their local shelters.
I didn't get a dog from a GSD rescue, because of the scrutiny and degree of vetting involved. I understand the need to find a good home for a dog, with a responsible owner. I, also, feel that it can seem like it might be easier to adopt a child. I guess I wasn't up the the scrutiny at the time, so I purchased from a breeder.
Rescues likely prevent some adoptions that shouldn't happen. I wonder, however, about how many people would have been great pet parents, if they weren't denied an adoption or scared away.