Whoa! Even the Clinchfield took longer than that.
Listen to Uwe. He's an outstanding talent. He didn't make the Milwaukee Road on Day 1 by hoping he'd get 50 people to post "Good work!" on the forum. (How many of those posts is enough, anyhow?) And that certainly isn't the reason I built the V&O, the NYS&W, or any other line I'm working on.
The #1 reason you build a rail line or Trainz object of any kind is for YOU. It needs to be done because
it needs to be done. Period. Those modeling narrow gauge lines in Thailand or the monorail at Jungle Jim's won't likely be interested. Oh well. The point is, do YOU enjoy it? If the BB isn't your cup of tea, then by all means move on. Maybe someone else would like to collaborate on the BB.
Taking breaks is often needed to complete big projects. Few of us are as focused as Uwe is on the Bitterroot Mountains (assuming he's not working on other projects that we don't know about, of course). When I tired of the V&O, I worked on the Susquehanna. When placing one building at a time bogged me down in Paterson, NJ, I worked on the C&IM. When putting fences around farm fields got slow, I moved on... etc.
You have shown tremendous improvement on the BB from your first pics to your most recent. The attention to drainage, engineering, topography, and the arrangement of mankind around the tracks shows that you have invested a lot of energy into studying how the real world is put together. Detail takes time and
pays few dividends unless someone sees the final product for the first time (or you offer it as
payware :hehe

.
I wonder how many Americans see "Buckingham" in the title and assume this is a British branchline! Who knows. I, for one, can't wait to see your finished product. Then again, I can't wait to see MY finished products! I started the V&O in 2003. I have redone the track at least three times, the texturing four or five, crossings three times, etc. It's been a PITA, but at the same time, when I haven't seen it in six months, then take a ride on train 261, I can almost enjoy it! :hehe: I started the Susquehanna in 2005 or so. Prototype-based layouts take time. That is one reason I have focused on model railroad trackplans, feeling that I may actually live to see the finished product. :hehe: Maybe you could take a page from the books of the real railroads and hire 10,000 Irish or Chinese laborers. :hehe: With the world in an economic depression, you might fix it right there.
If feedback is what you want, consider making a video like Uwe did for the Milwaukee Road. He inspired me to try, and so I finally downloaded Fraps and HyperCam2, plus I am working through the "SimpleLoco" tutorial for GMax so I can get the USRA heavy 2-8-2 I want (another long term project that won't gather more than ten people on a forum thread, but will get dozens of downloads). Maybe a few Youtube links will get you the feedback you are looking for.
The best advice I can give is lather, rinse, repeat.
Keep your stick on the ice!