Maybe writers room like environment was the wrong term, but I thought I had read that the Marvel production team, producers whatever, were treating it like a tv series with like season outlines just to know where they wanted to get to.
Im super interested in BTS stuff, behind the scenes not the Kpop group (although my kids like them). Anything that you could guess at or explain without legal peril would be delightful, Tank. :-)
Marvel's method for years was to develop content internally by having low-level writers working as staff hires. Meaning, they were paid a weekly salary, given properties to develop, and wrote treatments (2-10 page ideas). It was uncredited. These concepts went to a brain trust of sorts of writers from Marvel comics, who would offer input. The treatments were reworked based on this, and in a few cases, like with the first GOTG, a first draft script would be made. From there, the treatments or rough scripts would then sent out to writer/directors who would pitch their take on the idea.
Said writer/director who got the job would then make it their own thing. This was what they did in phase 1 and 2. During phase three, Marvel Studios, Marvel TV, and Marvel comics became more fragmented and the brain trust was no longer employed. As most of these movies were sequels, the internal development stopped. For the New movies in this phase (like Ant Man) they sought out known writer/directors who had a love for the source material (like Edgar Wright for Ant Man). Phase four was everyone sticking with the teams that each individual film had developed, save for the Russos replacing Whedon as the Avengers godfather.
Lucasfilm's approach was similar, but different. They started with Lucas having already laid some groundwork for the ST. Their first step was not to hire writers, but concept artists to generate visual ideas. Some based on what ideas Lucas had, some were told to just go wild. When JJ was brought on, a small brain trust was formed amongst the ST directors, Kennedy, and Simon Kinberg. They laid out a basic foundation of what was to come, but then everyone went off and did their own work individually, with information being shared. Trank and Treverrow got themselves ousted, while R1 and Solo both ended up getting massive reshoots with second directors. While there isn't a permanent brain trust, there is a story group that is supposed to keep continuity intact, but also functions to develop concepts internally, by mining the old EU and other SW material. These concepts are out there, and they take meetings on them to hear pitches, and if they like it, they'll develop it further. This is why we hear about a Yoda movie, an Obi-Wan movie, a Boba Fett movie, etc. These are concepts they are considering, and they may even be commissioning scripts, but non have been greenlit, and they are likely actively on hold after Solo. They also hear pitches on original ideas from people who have big clout (like say, if you made Game of Thrones).
The idea of working a film franchise with writers working in a TV style room is a relatively new idea. The DCU was doing that to a small extent. The Dark Universe was doing it, but The Mummy got them shut down. Last I heard, The Transformers franchise is being handled this way now. That room was responsible for Bumblebee, which is considered a victory. I've heard of other franchises having rooms put together -- GI Joe and Men in Black come to mind, but you never know if anything will ever get made.