Too bad my wife’s risk tolerance prevented me from making more aggressive moves earlier on, but every property has cash flowed within a year and none have been negative.

Or maybe you need to find another market that is providing high enough returns to justify the time, money, energy, etc spent in putting together a deal relative to your personal risk tolerance and the oppertunity cost of devoting your resources to RE vs other investment opportunities. 

I refuse to do it, but my wife can tolerate it enough to get the job done. 

Let's show a little tolerance, shall we?

It all depends on your risk tolerance and personality.

Zero tolerance for late payers.

I'm moderately risk-tolerant, I want my downside to be "make less money" (and break-even if the wheels fall off) rather than "come out of pocket".

That changes my risk tolerance and the way I leverage as well.

Seems like the answer in this case is one of balance: how are you balancing your progress toward your goal against your tolerance for risk, or at least that's the way I'm currently thinking about this thanks to this thread.

To me the answer is about gains but also Risk tolerance.