I find that if I am waiting at either end of the tram and the tram is not in sight, I can walk to the middle station (where the SC is) as fast as or faster than waiting for the tram. But for the entire length of the concourse, better to use the tram.
Same...if I just missed the tram, I'll just walk to the SkyClub rather than wait. But full concourse and I'll wait for the tram.