Tried another one. Decide I'd see about a all-rail-no-industry start for a change. Well, that didn't last long. Definitely not the seed for it.
Started the game up again, and this time I got a
really unusual seed. Masses of unused pulpwood and logs around Daugavpils, and stack of milk all down the river to Riga, and a seeded Dairy Processor just outside the border of the Riga territory. This was just
begging for an industry start, so I went with that. Paper Mill at Daugavpils initially (good returns, no bond) followed by Lumber Mill, then bought the Dairy Processor, and followed that with shipping the milk and lumber down to Riga.
Stayed out of Meat Packing Plants this time, due to competition among them, and just shipped their product. The whole economy in this seed was unusual for this map. Automobiles shipped to Pskov fairly easily, which is really weird. There were logging camps near Ventspils, so a Paper Mill on a short line to Ventspils took care of the Paper haulage while I was sorting everything else.
The Dairy Processor at Riga was a gold mine, and made the Cheese to Liepaja easy to accomplish. Milk supply was so consistent that I ended up running
two,
upgraded, Dairy Processors right next to each other, and they were both consistently returning annual profits in the $600-700k range. That is unprecedented for any map, in my experience. Usually it's a struggle to run one and get good returns.
Didn't bother buying into Estonia at all, since I figured the bonuses for those connections weren't really enough to justify the diversion. Kolka is worth doing though. It costs about $400k from Talsi (where you need to go anyway to get to Ventspils) and the $1 million connection bonus means you make an instant $600k on the deal even if you never use the line to Kolka. I did buy into Poland fairly late in the game, due to its cheap access cost and some good haulage there.
Ended up with a Gold in December 1936, which is the earliest I've managed to finish this scenario since the v18 changes.
Speaking of access costs: Lithuania is pointless. There's never any need to go into that territory. The Oil Refinery at Mazeiki, if it seeds, will make good money if you ship oil to it from Oskov. The problem is that when you add the territory access cost to the price of the refinery, you end up with an "asset" that will only give minimal profit in the time remaining. It's always pretty late in the game by the time the refinery gets going. First you have to buy into Russia and build rail there, which will set you back about $4 million even if you already at Russia's border, then you have to get trains all the way from Oskov to Mazeiki, then the Oil has to get from the station to the refinery. The better opinion is to just let the refinery do its own thing and ship the product.
However, I think the best option in terms of quick returns would be to just build your own refinery at Oskov. I haven't done this before, largely because I think the oil trains are fun, but it would be the smart option. It would be cheaper than buying into Lithuania and then buying the (cheaper, seeded) refinery there, and production would start instantly with zero oil shipping time. The resulting diesel can be shipped anywhere you like, so haulage on Diesel should be just as profitable, but you won't need specialised Oil-to-Mazeiki trains. You'd miss out on the haulage for Oil, which is very lucrative for the first four or five loads, but OTOH you'd get refinery profits and Diesel haulage profits almost instantaneously.
Furthermore, by the time you get into Russia there will usually be a stack of about 30-32 Oil at Oskov, and the warehouse makes another 8 loads per year. Put those together and the result is enough Oil to run an upgraded refinery at full capacity for four years. If you are four years or less from game end, you can upgrade your refinery as soon as you build it to maximise your profits. If you are (hypothetically) six years from game end then you could either upgrade the refinery after two years, and let it run at full upgraded capacity until game end, or you could upgrade it immediately for fast profits and let it run at half capacity for the last two years.
Edit: Just tried a quick test of this idea. I forgot that with the Oil price at $0 at Oskov, the warehouse only runs at 50% production. That means 4 loads/year instead of 8, so an upgraded refinery will start running out of oil in less than three years in a Depression (what it was when I tested), and probably close to 2 years in a Boom. This means it's not worth upgrading the refinery until the last year or so, if then. Better to take more consistent profits from a basic refinery.
However, the upgraded one returned 41% ROI in the first year, and 39% ROI in the second year. Since the upgrade doubles production but only requires 58% more cash up front, ROI for a basic refinery should be in the 30-32% range, with Oil price remaining near $0 for some time. The only thing to watch is that Oil will be worth $20 or so a load in Riga, so you have to be careful to not use an auto consist if shipping direct from Ostov to Riga. Trains from Ostov are fairly lucrative, with much faster turnaround than shipping to Mazeiki and back.