Photo requests rely on volunteers living close enough to a cemetery to be able to complete a request and to also have the ability to find the grave requested.
Some cemeteries are remote and a volunteer may have to travel an hour or more to get to it. When they get there they still need to be able to locate the headstone...this can be very difficult and time consuming if the cemetery records are not readily available.
I waited 18 months for photos from a cemetery in the middle of a very large city in England...sometimes you just need to be patient and keep hoping someone will eventually get to it.
Hope this helps,