How I thread a ribbon fully depends on the type of vibrator a machine has. In most cases I have the ribbon already attached to both spools first, then I drop both spools on their respective capstans and then load the ribbon onto the vibrator. It's pretty rare that I would literally thread the ribbon from one spool through the entire ribbon path to the opposite ribbon.

As many different types as there are manufacturers. Granted, most are very similar, but there is a big discrepancy in the more extreme variations. Some have folding gates that you open and close to drop a ribbon in, some are single-sided, while others have elaborate bends that are a pain to work a ribbon through. Why are they different? I suppose it's partly because of a domino effect created from all the other parts being different such as alignment guides, segments, type guides, carriages, etc.