Ken Birdwell's overview of the design process for HL1 is pretty interesting. Really shows how the culture at Valve was very AnCom in many ways.

https://www.gamasutra.com/view/feature/131815/the_cabal_valves_design_process_.php?page=4

The Workers Control the Means of Production

Even with all emphasis on group activity, most of the major features of Half-Life still only happened through individual initiative. Everyone had different ideas as to what exactly the game should look like, or at least what features we just had to do. The Cabal process gave these ideas a place to be heard, and since it was accepted that design ideas can come from anyone, it gave people as much authority as they wanted to take. If the idea required someone other than the inventor to actually do the work, or if the idea had impact on other areas of the game, they would need to start a Cabal and try to convince the other key people involved that their idea was worth the effort. At the start of the project, this was pretty easy as most everyone wildly underestimated the total amount of work that needed to be done, but toward the middle and end of the project the more disruptive decisions tended to get harder and harder to push through. It also helped filter out all design changes except for the ones with the most player impact for the least development work.

the HL2 cabal process was tweaked a bit:

https://www.gamasutra.com/view/news/259479/Classic_Postmortem_The_making_of_HalfLife_2.php