Writing is quite different as a discipline and in its effects when it's for self-discovery, self-analysis, messaging others, etc.
It's like the vast differences between relaxing alone at home, caring for your partner, hosting guests, going to work, taking kids on vacation...
What's helpful in either case is the ritual of entering that domain: you pull yourself together for work, dissolve on the couch, and put on a happy listening face for the kids. The more consistent you are in your rituals, the more quickly and deeply you enter and exit that domain.
That's how to escape mental defaults: have a huge variety of them, widely-spaced, so you can introspect their difference and play their respective lights against their shadows.
It's like the vast differences between relaxing alone at home, caring for your partner, hosting guests, going to work, taking kids on vacation...
What's helpful in either case is the ritual of entering that domain: you pull yourself together for work, dissolve on the couch, and put on a happy listening face for the kids. The more consistent you are in your rituals, the more quickly and deeply you enter and exit that domain.
That's how to escape mental defaults: have a huge variety of them, widely-spaced, so you can introspect their difference and play their respective lights against their shadows.