I do outline for most of my stories, but what kind of outline I make and how detailed it gets depends on the story. I have some outlines that are chapter by chapter or part by part, for Secrets of the Heart and my two collaborations, but usually I'm more of a timeline person.
My Curtain Call outline is basically a timeline, with a bunch of research at the bottom. The way I'm writing that story is, I'm God of the story, and I get to decide what situations to put my characters in. But since they have free will, they get to decide how to react. So I have various points along the way that are planned out and set in stone, but how the characters get there and what happens in between is decided chapter by chapter, as I'm writing.
Then I have Guilty Roads, with no outline whatsoever, only an idea in my head of where I'm going with it. That scares me a little, but we'll see how it goes.
It's weird how I've grown as a writer.
At first, I never outlined anything. I had an idea and just went with it. I'd sometimes knew how it would end, sometimes not. It probably explains my ADD back in the day though with 50 stories going lol. I mean I still have a few at the same time, but I've gotten WAY better over the years about sticking to it.
For collabs, it's like you said, we have chapters planned, but we've definitely tweaked it when something called for it. It's a chapter by chapter, but flexible, especially if the characters decide to throw a wrench in the works LOL. I feel with collabs you need outlines, or things go awry way too easily.
For my own now? I'm more of a timeline person too. I know with "Remember Me This Way", all I have is a set list of events I need to happen and the time frame. After I've already written/posted the chapter, then I'll add it to the event on the timeline just so I can reference back to it if I need to. It's like you said, sort of playing God lol. There's events that happen, but there's definitely free will. And there's been times Nick's decided he's going to change things up, and I went with it. But I do know exactly how I'm going to end it.
Oddly, "Walked Out Of My Dreams" has a chapter by chapter...well it's not even a concrete outline, more like who's POV, and what
may happen. It's already changed once lol and it's not even that far along. But I do know how that one will go and end.
So I guess it depends on the story anymore, but there's usually some guideline just so I don't mix up anything.