One challenging thing about the construction of a model railroad is that the time available to dedicate to construction is limited. For me, my life is centered around my baby daughter and my wife, as well as a full-time career; all of that is in front of commitments to family and friends. Then comes the model railroad, which splits time with activities that involve 'real' trains. And even time allotted to the layout is split between operating sessions and actual, physical construction of the layout or of equipment.
Because of the limited time available to dedicate to progress on the model railroad, there is no current part of the layout that is finished. It has been about 6 years in construction, including preparation of the space itself, and yet there are years more to pass before much of the layout will have any finished scenery. Therefore, when I am able to install something that will be visible on the finished product, I am excited to be working on something 'final.' The track and signals atop the railroad fall into that category, and so do the local control panels (LCP's) that allow for local control of the interlockings.