*nerd glasses* um, technically, warriors has much more books than wings of fire, is really old and is still an ongoing series, so warriors is actually longer
there are 8 main series books, with 6 in each arc, with the exception of A Starless Clan, which currently has 3. There are also at least 15 novellas and almost 20 super editions, meaning there would be at least 70 books in total