Bad example. Star wars premiered as just “Star Wars”. The episode IV monicker was added in later remasterings of the film. It was indeed episode four of a six part saga Lucas wrote. But it was filmed first, as it was deemed the easier and cheapest one to film. The original script was a mess, and it was Lucas’s wife who salvaged the movie by cutting about a third of unnecessary fluff and bad dialogue that Lucas had filmed and editing the whole deal as a traditional hero’s journey.