In installations like the one linked, when the panels are recessed, do you tend to use a flat panel (e.g. MDF) or leave it as wall? I would imagine it's usually a panel, in order to get a smooth finish?
If I were to do it in my own house, I'd use at least poplar rails and stiles (styles ). If I wanted a full 3/4" reveal then I would probably put a 1/4 backer sheet against the wall first (mdf) and then apply the frame over that. If I want a lesser reveal, then I'd rabbet out the back of the frame and pop in 1/4" material to get 1/2" reveal.