Writing is thinking

You don’t need an audience to put writing work for yourself:

Writing can let you access things you know but can’t access deliberately. This is a powerful and utterly counter-intuitive insight.
Writing down assorted ideas as they pop up in your mind will bring all the benefits you are looking for here. In my experience, formalities such as templates or formal notations are counterproductive when it comes to thinking.
Text is the best design tool for approaching a problem when uncertain. Once you have learned as much as possible about the problem, try writing down a high-level description of the alternatives for yourself
When it comes to modeling software, compared to plain English, every other notation usage is marginal in practice.
When stuck debugging a tricky problem, write a note articulating it. Rubber duck debugging is a thing, after all.
An organization that favors long-form writing favors thinking by design.
If something bugs you, write all your thoughts about it down. More often than not, this brings an immediate relief.
Authenticity concerns aside, a powerful reason to NOT use ChatGPT to write stuff on your behalf is that it will prevent you from thinking.