During the 20 years I was travelling into and out of Hong Kong on a frequent basis, sometimes a couple of times a week, I never saw an escalator or a walkway out of service. Guess its down to the quality of what was installed in the first place and having an on-site service team as they must do with the number of escalators they operate. Incidentally, it was highly unusual to see an escalator out of service anywhere in Hong Kong whether it was in a mall or the kilometre long Central Escalator which goes uphill most of the day except for a short period during during morning rush hour when it reverses.