This series is much larger in scope and generally complex than a medical procedural or family sitcom, which are the (increasingly rare) types of shows that reliably deliver a season a year. The effects alone will require a lengthy runway, and you're underestimating the amount of writing that will need to be done. A better comp is something like HBO's own Game of Thrones or House of the Dragon, which... has massive, year+ breaks between seasons.
It's a valid concern.