Properties in how many MSA's is enough to be diversified?

[Mark Mosch]

This is aimed at some of the bigger investors out there with multiple properties:  BP helped me get started about 2 years ago.  I was able to lever smaller properties I had and show a track record that enabled me to syndicate a $4 million fund, then another $15 million one.  I'm almost done deploying the second fund and am now about to start on the third.  We are approaching 1,000 units owned between Northwest AR, Kansas City, Little Rock, Montana, and St Louis.  My investors have been talking about wanting to make sure we are diversified enough so one regional downtown won't kill our whole return.  So I was wondering - do I keep looking to get into new places or double down on the areas we have experience with?  I know some bigger guys like Ken KcElroy go really heavy into maybe just 3-5 metros around the US.  So - I'm wondering if any of you can weigh in on the benefits of being in many different areas vs the benefits of being more concentrated in fewer ones.  Thanks in advance for your thoughts!