Royal, it is a large contributor to my hunting technique, while hunting Kudu, zebra and other species that frequent rugged mountainous terrain either myself or Joe will identify dens, these are quite easy to see due to the trampled foliage and large amount of dung (almost midden like).
Dens can be a slight over hang (rock) or a shallow cave like structure (crevasse or proper small cave)
Once located I will often hit the opposite side of the valley (hopefully on a different day, as the Waterberg are only foot hills until you start climbing them
) as the sun reaches the above mentioned locations and glass these dens for potential quality rams.
I have found that glassing these dens in the afternoons are often ones best bet, for obvious reasons.
In my experience, pairs and family groups will Den, I am unsure as to solitary bucks but on the other hand solitary males are not a common sight (at least not in our area) klippie always tend to move in family/breeding pairs either ram and ewe or one or two younger animals included.
My best always