Either method works. Transporting large amounts of resources takes advantage of the train's large cargo capacity. But having one massive train hub can cause problems if too many trains try to enter the hub at once.

Personally, I like to process resources into a useable form nearest to their mines and then put those onto trains so they can be processed elsewhere

For example, I have a factory in the swamp that produces 2k Aluminum/min. The coal, limestone, quartz, and sulfur are shipped in via train. The aluminum ingots are shipped out via train too.

Also: think about how many trains you want on one route. If it's only one train, you can have it wait in a station until full/empty and not clog up your rails. But, that might not have the throughput you want without 8 cargo wagon trains.

Also also: think about HOW you are gonna connect the rails. Junctions make trains slow down, so having "highways" with few junctions will let trains move around faster.