There's a great discussion to be had in scaling your practices to the human factors.
For a solo developer, just breaking things out into modules and massaging the formatting is likely to be a net negative - something you might do once you've accumulated months of cruft and are ready to start handing it off to others or repurposing it for a new project, but also a chore that will get in the way of thinking about the job in front of you right now, a temptation to think top-down planning will come to your rescue. Your advantage is in being able to change direction immediately, and there are a lot of ways to give that up by accidentally following a practice for a larger team.
As a team gets bigger, it's more important to be cautious because of momentum; any direction you pick for development will be hard to stop once it gets going.
At the same time, there are processes and automations that help at every scale, and at the small scale they're just more likely to be little scripts and workflow conventions, not ironclad enforcements.
For a solo developer, just breaking things out into modules and massaging the formatting is likely to be a net negative - something you might do once you've accumulated months of cruft and are ready to start handing it off to others or repurposing it for a new project, but also a chore that will get in the way of thinking about the job in front of you right now, a temptation to think top-down planning will come to your rescue. Your advantage is in being able to change direction immediately, and there are a lot of ways to give that up by accidentally following a practice for a larger team.
As a team gets bigger, it's more important to be cautious because of momentum; any direction you pick for development will be hard to stop once it gets going.
At the same time, there are processes and automations that help at every scale, and at the small scale they're just more likely to be little scripts and workflow conventions, not ironclad enforcements.