My 2-rail layout has been operating reliably for almost 20 years without any problems related to the track or switches. All freight cars are fitted with Intermountain wheelsets riding in Athearn trucks, which don't require lubrication. I don't think I've ever had a Kadee coupler fail, and the worst mechanical problem in recent years was a loose eccentric rod that fell down on the ballast struck and stopped the engine because the small screw holding it to the eccentric crank had fallen out. Fortunately, I located the screw a few feet down the line and was able to put it back in place and secure it with a tiny drop of Loc-Tite. This was on a Sunset/3rd Rail model, so the same thing could have happened with a 3-rail version. Of course the engines need a little oil and grease from time to time, just as their 3-rail cousins do.