I love this excellent Eleganthack post about writing daily. Aiming to form a more regular writing habit by short daily attempts, rather than annual marathons.
Daily (or most-day) habits are a good way to stick to things. You quickly identify when you stop doing something if you miss a few days. Then you can either correct it and resume, or decide it's not worth it and move on. Dropping habits that you don't miss is as important as adding new ones - you cannot add activities ad-finitum to a finite day.
The idea of 15 minutes writing then five minutes editing is a nice starting point. I'm interested to see how it develops; in particular if I can start using the 15 minutes for Hemingway-mode style writing with no deletions, rather than wasting valuable seconds rewording the previous sentence. As for editing in five minutes, beyond proofreading and minor fixes there is not much that can be done in five minutes. Maybe some basic structure changes, and spellchecking my broken keyboard typos.
I am often stuck on the "what to write" front. I take a lot of notes, but spread between dozens of different files and formats. Committing them somewhere more central is a good way to try to flesh out the thoughts more than simple two-line scrawls.
The distinction between private and public writing is also interesting. I've never tried to journal or otherwise transcribe my inner monologue. I'm quite curious what that would look like. I think (without having tried) that it's important to differentiate between private and public writing. When writing something not intended for anyone else to read, you can be more direct, more honest, and take more shortcuts. I know what my stupid 12 character acronyms stand for, and like not having to expand them.
Whether the 15 minutes alternates between public/private, or changes to 10 minutes, or something else, remains to be seen.