When writing, you should be able to change your mind about your first idea, instead of being compelled to stick to it. This freedom signals to your brain that you are in control and this sense of control goes a long way in the writing process. It allows you to use curiosity to guide your thinking, which in turn, brings you to so many other places, increasing your chance to capture insight (insight cannot be predetermined; writing that aims at insight must be organized in a flexible system).
References
Ahrens, S. (2017). How to Take Smart Notes: One Simple Technique to Boost Writing, Learning and Thinking – for Students, Academics and Nonfiction Book Writers. CreateSpace Independent Publishing Platform.