Well it sounds like they are starting to figure it out, at least for SW. They are doing 12 episodes for Andor, and from all reports it actually feels more like a TV show and not a extra long movie. They've even said it's likely to have a season 2 with another 12 episodes.
I know when they announced 18 episodes for Daredevil Reborn that people got nervous since most agree the Netflix shows were all at least 2-3 episodes too long. But if the choice is too few episodes to tell a good story and too many that they need to add a filler episode or two, I'd rather have the latter. Although, I hope they do more of a 2-3 story arcs thing that tie together at the end.
Not every show needs to be 8, 10, 12 episodes. The problem is you can't have the amount of story to tell that they've tried to tell in 6 episodes. F&tWS is the best example of this. You can't have the Power Broker, Flag Smashers, John Walker, who is going to be Cap going forward, Baron Zemo, etc. all happen in 6 episodes. It's just impossible. There needed to be about half that stuff for it to make sense as a story, straight up.