General: Production is demand-driven. If the sawmill doesn’t have any customers for its goods, nobody will produce anything. You always have to set up the complete chain at once.
(There may be some production even if you’re just supplying raw materials, because of the automatic transport. However, if the sawmill started out with a production of 0, it’s likely that there’s no city in the vicinity to create demand, so it won’t do anything on its own.)
For the whole process, it works imho best to think it backwards: The city needs goods – how to get them there? And from there on down to the raw materials.
I actively try to avoid thinking about frequency. I do stuff and hope it works; if not, I change it or do something else. “Shorter time is kind of better, except when it’s not” works, so far – on easy. 😀 The whole thing is very vague, I fear that the meagre scraps of information given by the developers only obfuscate things further, and the game does a spectacular job at not providing meaningful feedback.
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Update on the supply chain above:
It’s not the iron itself that’s buggy, it’s the station or lines. The game can’t seem to cope with TWO kinds of cargo waiting for the SAME line and direction. Just imagine: TWO! Not one! The sheer complexity!
Anyway, what happened: Somehow, the transfer station switched from “eating” all the iron to “eating” all the coal. I suspect that my trucks cleared the station from all coal waiting there, maybe even managed to get it all to the factory before the next train arrived. When it did, it was the iron train. From then on, the iron waited in the station, as it should, and was duly transported uphill by the trucks. Instead, all the coal disappeared, as the iron had before.
A few years later, it went back to coal.
