80+ hours into Red Dead 2, and I'm only at 56.6% complete. I'm betting the second half's playtime won't double the total playtime through, since I'm close to being done with the pelt collection portion. That sentence sounds kind of negative, but it's not, I've had a blast just riding around looking for things so the story's taken a backseat. I am in Chapter 4 of the story, and just completed the first/only? quest under Sadie's name - no spoilers, but you would definitely remember this one.
I'm also about 70% done with Yoku's Island Express. I finished the main story, and now I'm working on all the collectibles. Really fun game that doesn't overstay it's welcome.