My productivity app is a never-ending .txt file (2020)

I used to have a zillion todo txt files in the early 2000's, migrated to OneNote around 2005 and have been using the same OneNote notebook for 20 years now. My life is in there - 20 years worth of todos, lists, thoughts, ideas, etc.. always evolving, perfectly synchronized across computers and mobile. I'm referencing and updating my OneNote all day as I get things done, have ideas, and think of new things to do, or things to remembers. It's an extension of my brain at this point.

I've tried alternatives, but OneNote has been simple and reliable, it just works everywhere. Probably one of the most important apps in my life.

Could you please say more about your day-to-day with OneNote? How is your notebook organized, how do you add to it, how do you review it, etc.?

Same but with Keep and GDocs. I still use a local neverending txt like TFA though, as a short-term todo list + clipboard. Short thoughts and little factoids like license plate numbers, appointments, and restaurant recommendations go on Keep (although some of those "short thoughts" have ended up busting the character limit). Refined structured notes end up in a GDoc by topic. Some of my GDocs are now the size of small textbooks. I also love Google Takeout so that I can backup it all up periodically.

I would say, just as you would about OneNote, Keep is one of the most important apps in my life.