I know what you mean in terms of 3D modelling, I'm creating all custom stations and industries, so I have a lot of small projects to learn on. I have stations that are on the ground, stations that float, stations with purposely separate tracks so that a junction can be built in between (like I did between OTC and its small locomotive facility, and a station on the the Milwaukee District West line), OTC still not an "industry" it's just an object with track attached. I'm doing all above ground work before working on Union Station and Millennium Station and their respective approaches, or the CTA. I did decide today to just reinstall the terrain and start grading, so if I suddenly stop reporting on this again, I've gone insane and I'm hospitalized.
I look at it as if I'm building a model railroad, I want the benchwork and track done so I can run trains, I'll create mockups of stuff I need to do that, but getting the track working first before needing to destroy the scenery to adjust the track.
I developed a new honest metric for determining where I'm at, based on length of subdivision, total industries/stations, and crossings, and how much farther I have to go. CSX, Metra, NS and a couple other lines are not yet included because their length is unknown. The "Line Total Miles" column is what is modelled, not the actual length, the BNSF Aurora Sub is definitely more the 7.10 miles but that's all I'm doing.