I like how simple this feels. This post has some details about the personal system that I have been using for 10 years now. My 10-19 captures most of my personal life as per that post.
I then have 30-39 is the company that I run (just a single person thing so it doesn’t need to be big), it has finances and contracts etc.
Then my remaining areas I use for the larger projects in my life. So Johnny.Decimal started as 50-59 (but has now grown to be its own project.
Yeah I don’t see anything wrong with that.