Except that speculation is (historically) the norm in cases where communication is limited to speed of travel. Freight only takes over dominance as the mode in the atlantic when telegraph cables went in.
Do we know anything at all about the regular freight business? (As opposed to the rules we have for the free trader business that touch on freight). Freight may be a very small part of the regular business.
On the other hand, if a company has a ship going regularily back and forth between two worlds, the shipping part of the business may be effectively the same as freight business. The company factors has to buy X tons of goods every 20 days and have it ready to load; they also receive X tons of goods every 20 days and have to sell that. The business the factors conduct may be speculative (though not necessarily always), but the ship earns the same for the shipping division no matter what.
Hans