IIRC, the original trailer of the game from like 8 years ago was actually an advertisement for developers back then, and future to join CD Projekt Red when they didn’t have enough people to make the game. Despite people wanting the game out to be sooner, It’s more than likely that their Board of Directors wanted the game out sooner to increase their profit margins quickly as the time between releases between a haphazardly made game and a polished RPG would’ve cut into their yacht funds. Which is absolutely insane, especially since a game this ambitious should’ve taken much more development time.
According to Eurogamer, it’s been worked on for about 4 years, right after the Blood and Wine expansion was released with 50 staff members (It expanded over time). With two years of pre-production and two years of actual game development. For a game this ambitious, it’s definitely supposed to be a six year project, especially since a lot of the features that were planned were ultimately scrapped and changed mid-development.
However, in general, games that have been worked on for so long, probably aren’t actually worked on for very long. With many that get released being stuck in “Development Hell” for years due to multiple factors.
Prime example would be Duke Nukem Forever, of which, when released had lines, references and attitudes that were at that point years dated. 10 years since the game’s announcement and it turned out to be a total flop.