But he was smart enough to only take over properties with equity so he was able to refi out of them before the underlying lienholders could foreclose.  

I might try the “emergency service” which is $20 with limited data and just use that for the smart locks and ring cameras.

Starting small with one property was a smart move, especially in a new market.

to your point, if you save up so that you're in a strong financial position, house hack a solid duplex in a decent neighborhood, make smart decisions, and hold it indefinitely, you'll be fine.conversely, if you have $0 and somehow start out with a risky flip, or borrow $20K and spend it all on a magic mentoring program, or buy a terrible property in a neighborhood you've never been to, you may not be fine.

In my market there are 2 reasons that keeping is smart.  1) the historical long term appreciation is on going, going back to when records started tracking the appreciation 2) the property tax is near fixed cost.  

If your properties are generating solid cash flow or have appreciated significantly, you might be following a “smart leverage” strategy, à la Grant Cardone.

Install low flow water heads, swap the washer/dryer with High Efficiency models, replace the water heater with a tankless version and lock the temperature at a reasonable level, install smart thermostats that will automatically reduce the heat/cool when it senses no one is home, swap all the lights for LEDs, etc. 

But in smart buying, if someone has enough cash to pay cash for a property, they could easily stash a good chunk of that away to cover downed months and still leverage to increase the overall returns on their portfolio.

This is a great idea that I think I will incorporate.Your point about a contingency line item is smart, I will need to talk to my lender about that possibility. 

CA maybe as high with their EIR requirements that cost 250k to 500k just for the EIR reports.That's a really smart way to go about it.