I just remembered I had made myself a "speed reading notes" file that's even more .... noted than the chapter cheat sheet. That cheat sheet is largely meant to help me navigate around but for some more detailed things of note, I ended up starting at looks at the image below Uh............ I'm guessing ch83? Somewhere in there. And just read and started making more navigational notes for myself on what I've included that is important moving forward. You can see that these don't have chapters assigned to them and it's just raw of "this is what happened in this order".
(Image below is an actual spoiler for NTN sooooo yeah)
Summary
I recall with the large fanfic project I did forever ago, I actually named the chapters back then lol But I had like one or two sentence summaries, or a very brief paragraph, telling me about what was in each chapter. It was started after I had done a good portion of chapters, but as I progressed, it ended up turning into stuff as an outline. Ultimately it is what caused me to stop working on that story because "well now I knew the ending" and it was no longer fun. [Plus I had to kill of my favorite character and instead of not killing him off, I just went nope this is a fanfic and I can clearly put this much effort into a 100% original story. Yep yep. That's totally the reason. And I'm sticking by it. To this day.]
@allenT - I really like your idea of using notepad+ cause omg is that a super nice program.
Another small program I enjoyed using for notes and such is just plain WordPad. But I do recall trying out... Think it was called "ZenWriter"? My only problem with it, is it's soooo scaled down, that it doesn't support italics and such and saves as an .rtf. So I'd still have to modify stuff.