If it's concentrated it is subject to event risk and other risk types that are isolated to that concern.  

I know many property managers in Las Vegas, but only two of them are skilled in selecting reliable tenants.Selecting a tenant segment with a high concentration of reliable tenants.

Single-family homes with a casita/guesthouse can bring a premium - still those tend to be concentrated to zoning available on older homes in the Central Valley, an area that has already has seen extreme appreciation due to the revitalization of Downtown over the past decade.  

If your goal is a reliable passive income you will not outlive, then select a 10 assignment with a high concentration of reliable tenants.A reliable tenant is someone who stays for many years, always pays the rent on schedule, and takes care of the property.

These are very few of the things you should consider, so concentrating your efforts in one place to start is probably a good idea.Please feel free to reach out if you have any questions.

If I were starting over, I would concentrate my efforts on producing content (videos, podcasts, websites, books, etc) about my specific expertise. 

There are so many ways to go and your feedback helps me know what has worked for others so I can concentrate my efforts to those areas.

Concentrate on the agents who do the most STR business, and they will refer you more often than agents who are generalists.

Also, in our scenario, the developer is only concentrated on development and is outsourcing everything else to a builder who has their own architects and designers.

If they kept statistics on it, I'm sure we'd do quite well in the lowest per capita concentration of attractive women statistic.