When I write long fiction, I almost always know the beginning and the ending of the novel - in fact, I usually can see those two critical scenes in some detail. Then I like to clearly chart my path from that starting point to the finish line. This road map might look more like numbered short chapter sketches than a hierarchical outline, but my brain works in spatial mode so that I'm always trying to picture the shape of the book, where the energy peaks and falls. I like to know clearly where I'm going, and how I'm going to get there. I allow myself to change things up if I find I've painted myself into a corner somewhere, but usually I'll stick to that road map pretty closely.
I know this doesn't work for everyone, and I really am in awe of writers who can just sit down with an idea and a general destination in mind, letting the story follow its own course. I'm the kind of person who packs for a trip days in advance, using a detailed list made the week before! I want all those details in place before I get on board and buckle up, so to speak.
Charting the plot of a novel is a bit like that for me, although maybe a little less controlling. But not much. It really helps me to visualize the storyline if I can see how many chapters fall into the beginning of the journey, the complications along the way, and the climax of the literary trip. I like to color-code these chapter sketches according to the energy level - blue for background narrative, purple for setting mood and atmosphere, green for rising action, and red for peak events. That way I can see the entire shape of the book at a glance, which helps me adjust things as I go along.
If I cut sections out, I keep the chapter sketch in place but redlined through, so I can see how that changes the dynamics of the book's ebb and flow. And if I want to use that deleted material somewhere later, I know where it came from in the storyline and what the motivations were.
Working from an outline like this also helps me plant things along the way and keep track of important plot points that I might otherwise forget or not pay off soon enough. It helps me keep continuity (along with many copious lists of people, places, things, etc.) as the book progresses.
I guess the point is that I'm an organized kind of writer who writes best with the road map in front of me. And if this sounds AR, you should see what happens when I write non-fiction pieces requiring a lot of research. I can wear myself out!