The length of time it takes to build a non-fictional route must be proportional to the length of the route itself and the level of detail required. For example, my Aln Valley route is three miles long, has two stations, fields, bridges and an industrial estate, and took me, from the day of my visit to gather information to the day I released it, seven weeks to build. But, I already had many objects I could use from my Tyne Valley Route, which, on the other hand, at about 65 miles long, will probably take about 20 months of spare time from start to finish (and thats without AWS); and, after that, I'll need to rebuild the bits I'm no longer satisfied with...!!!
The other problem with routes of great length is the amount of time it takes to drive correctly (Edinburgh - Aberdeen about 2hrs 45mins; even Hexham to Heworth, at about 26 miles, is just short of an hour). So, in my opinion, as a game, it's good to have a mixture of shorter, satisfying routes, and longer, demanding ones....
eezypeazy