New Data Suggests Long Waits Between Seasons Are Hurting Viewership on Netflix Hits
(www.whats-on-netflix.com)
I don't have any evidence of this so I could be wrong, but I get the sense that a lot of platforms are extremely risk averse to where they won't allow any work to be started on Season 2 until Season 1 is the mega hit they're expecting. Which is why so many of their shows get cancelled after 1 season. This extends production time because they aren't filming parts of different episodes concurrently and already accumulating footage they need for later seasons like many other shows do/did.
I don't think the wait between seasons needs to be as long, they just need to work more efficiently and trust/recognize when they have something they think will hit and when they don't. I imagine most shows people hate are also hated by the cast and crew before it airs, just like game devs know when they're working on and are going to release a bad/compromised game.