A lot of what I am seeing these days is not actual switches, but PIR switching on stairwells.
Where as a given flight of stairs might have a sensor on it, it will trigger on movement at the bottom of the stairs and also trigger a delay timer at the top of that set of stairs, that energises the next PIR (and lights) and turns off the lower lighting.
If it saves lights being left on all night,, I'm all for it.
Having said that, in fire situations, it's all lights on.
