Did they run into unexpected problems?

For power we installed an outlet in the attic which code calls for anyway.And as always you have your phone for seeing what's going on. 

And the other neighbor who had their electricity turned off was running a power cord from an outlet at the house, through a window, over the fence into their place.

Just make sure the support is replaced with a fan rated support so it doesn't fall on someone's head unexpectedly.

If any of that sounds helpful feel free to reach out! Let's

(Kylie Cooper / The Seattle Times)Several of the largest property management companies operating in Seattle conspired to drive up rents and decrease competition, three lawsuits filed this month allege.The cases, filed in federal court in Seattle, focus on the use of RealPage software, which gathers information about rental units and rent prices and uses an algorithm to recommend how much landlords should charge.The complaints claim that by exchanging detailed and “competitively sensitive” information, RealPage and the landlords have illegally created a “cartel” to set prices in violation of antitrust laws.The widespread use of RealPage has increased rents across the country and in Seattle neighborhoods such as downtown, Capitol Hill, the Central District, South Lake Union and Queen Anne, the complaints allege.The lawsuits, filed on behalf of tenants, cited an investigation by the nonprofit news outlet ProPublica that was published in October and detailed the use of RealPage in Seattle and other cities.

While, there is still significant upside on the properties with larger appreciation (I'm buying in the same place I live and the price has gone up about 50% in the 5 years I have lived here) and refinancing into lower rates, there is also pretty large downsides with problem tenants, problem governments and unexpected repairs.I have one friend whose brother did it for a while got up to 17 properties and then called quits and sold them all because the time commitment and stress wasn't worth it (even if the returns were there). 

As Jay pointed out, the primary risks are the project encounters an unexpected problem that results in increased cost and/or time.  

You always need money for the unexpected. 

Did I ever believe there would never be another unexpected earthquake?