I think they're one of those things that are very common but not necessarily commonly seen. I saw three over eight days, but this was the only one we got a good look at (largely due to being up against time constraints when we saw the others).
In my experience I also believe it is 'very common but not necessarily commonly seen'.
I got one reasonably good view and several more views which were just fleeting glances over 12 days in South Africa. I personally haven't seen the species in Kenya or Tanzania so I don't know how common that population is, but I believe it may be less common than the Southern African population?
Nopes, I do not remember seeing many outside Etosha during 3.5 weeks in southern Africa and here in East Africa I do work in semi-arid areas and in a montane rainforest, so dikdik & duiker habitat not steenbok. Though I haven't seen a single antelope here in Baringo so far....