I take more notes than I do write “formal” documents – meaning something that needs to follow a template, or needs pretty formatting for someone else’s consumption.
If I’m writing a formal document I usually keep the outline on the first page, work from it, and then delete it when I get to a stage in writing that is focused on editing and filling-in details. I don’t use Word’s or Pages’ outlining features – they are pretty much useless for the writing I do.
If I “jot ideas in a notes app” they are usually handwritten ideas, or a maybe a mind-map, or maybe for bigger or more complex things a concept map developed in Tinderbox and/or Curio. Only rarely do I move those things into Word or Pages – where I do most of my formal writing.
I also do a lot of PowerPoint decks because my clients are obsessed with this format(1) – these start with an outline then the pages get fleshed out, graphics created in Visio or elsewhere, etc. PowerPoint decks get a lot of collaborators putting their hand in.
I produce about 15,000 - 20,000 words / week for clients – counting all the revisions and collaborations – and these processes have worked out very well in my environment.
(1) probably contributing to the ultimate demise of civilization, of course