Would appreciate financial advice regarding 1% rule

[Terrell Garren]

59 years old with 16 SFHs near Charlotte, NC. No debt (please don't beat me up regarding no use of leverage - I'm an old guy and just don't prefer debt at this point in my life).  I do my own PM and set my rents around 10% less than market to retain really good residents.  What began as a hobby 8 years ago, allowed me to retire early and cash flow life. My real estate objectives were diversification from financial investments and cash flow.  Regarding the 1% rule, I generally turn .7 to .9%. Given that I carry no debt service and do my own PM, is this financially sound?

Thank you.