Apart from these percentages, healthy cash flow (i.e. income at least 1.5x monthly expenses) and the wiggle room to afford a visit from a handyman or a vacancy here and there are both soft metrics that I would focus on. 

You need to be putting away quite a healthy percentage for the later years.

I have experienced, first hand, so many healthy people drop out of the blue, as young as 40s, but often in their 50s and 60s.

She seemed pretty healthy and with it in the photos.

But don't worry...plenty of people have lived long, healthy, exciting, fulfilled lives on far, far less than $10K / month. 

Here's a healthy discussion of Pace Morby specifically.https://www.biggerpockets.com/forums/79/topics/1001612-pace-morby-mentorship

Thank you for your feedback in advance , be safe and healthy.  

* A one-week vacation around July, and 2 or 3 weekend-getaways throughout the year to decompress* Keep family healthy throughout the year, however we can, with safe social practices* Stretch goal: buy our first no-cash-whatsoever property (OPM)* Stretch goal: Buy as many good foreclosure deals as possible with other investors, if that's a thing in 2021

Even if you invested years later, there is still PLENTY of meat on the bone for a healthy profit. 

Beyond that, a healthy familiarity with the nuts-and-bolts of all things REI (market research, strategies, deal analysis, property management, etc.) goes a long way in communicating with the team and articulating exactly what you're looking for.