I currently have Don Ryan staying at my holiday apartments Flats in Luxor. He is ‘digging’ in the Valley of Kings on the undecorated tombs, here are some links to past lectures he has given http://luxor-news.blogspot.com/search/label/KV27.
It is thought that some of these tombs were for the ‘girls’ of the 18th dynasty. Stylistically you can date even a shaft to a period, I remember Otto Schaden explaining this at a lecture he gave on KV63. I asked him why the tombs were undecorated. It puzzled me as nobles tombs of this period are decorated so why not the queens. He thought there were three possible reasons, although there may be more 1) only kings tombs were decorated in the valley of the kings. There are a number of non pharaohs tombs and it may have been the “rules” that these could not be decorated. 2) (this explanation appealed more to me) that the chapels of these tombs have not been found and these were decorated. 3) the decoration might have been lost during the flooding of these tombs which removed the plaster work. It was a fascinating discussion and just shows you how much more there is to learn.
He is such an informative person, if you ever get a chance to go to a lecture of his do not miss it. We have chatted about Ancient Egyptian rope, funerary cones, his work in the valley, his work with Thor Heyerdale, Egyptology people he has met in the past and all sorts of other things.