For screenwriting I highly recommend checking out emacs fountain mode [1] (plus imenu-list and Olivetti minor modes). In combination with org-mode it is the most powerful writing/outlining tool you can imagine.

Also, if you haven't tried them, I highly recommend checking out WorkFlowy [2], Gingko [3], or Nulis [4] (disclaimer - nulis is my own project). Outlining and organizing projects as a tree structure is insanely powerful and convenient.

The idea of organizing a script/novel as a tree structure rather than a flat outline allows you to "zoom into" as many levels as you want, and conveniently focus on any part of your work. I recommend using separate branches for worldbuilding, characters, notes, and plot outline, summarize the high level ideas quickly, and expand on them by adding more levels.

Writing the actual draft though is much more convenient in emacs + fountain/markdown + org/imenu.

To take it to a crazy level of awesomeness consider storing your files in git, or at least dropbox, to have a history of revisions.

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[1] https://github.com/rnkn/fountain-mode

[2] https://workflowy.com

[3] https://gingkoapp.com

[4] https://github.com/raymestalez/nulis

Also, emacs/fountain screenshot:

https://i.imgur.com/AJpUNsz.png

Looks awesome, truly a pleasure to use.