Niche case: The other time I was departing/originating MAD but had to get a tax free stamp at the customs corner inside luggage carrousels hall, once done I could backtrack to departures and use (4) on Craigthemif's list but instead I used (1)/(2) since I was already there. However the queue was slow moving and bactracking to (4) would have been faster.
Living in Madrid I've never done a MAD transfer so I wonder for those who can use (4), which is probably everyone here on FT, do you use 1/2 or head out, up, and 4?