Benefits to investing in more than 2 different markets?

[Maxwell Lee]

We are invested in two very popular secondary markets for investors. Good cash flow, low price points, steady growth projections, and these two markets are in very different geographic regions. It seemed pragmatic a year ago to diversify to that second market and I am very glad that we did so.  

So now I am wondering if it's worth going after a third market. Anyone out there who has taken a DIY approach to REI (ie not through turnkey companies) and is actively investing in 3 or more markets (meaning not just holding rentals from once upon a time but still looking and buying in at least 3) care to chime in? Should I try to enter a different type of market (lower cash flow, higher appreciation potential?) and/or should it be in yet another geographic region? (I am strongly considering a number of cities that are located in the states we're already in)

I don't want to do it for the sake of doing it, but rather because there are tangible benefits. It seems the cons are rather obvious (diverting my focus and attention, having to find another network of professionals I can trust, less economies of scale, more travel) and I'm not sure there are a whole lot of benefits. Fwiw, one of the reasons REI has been such a good fit for me is that I am an avid traveler and passionate about cities/urban planning. So I already spend a lot of time studying cities and their history, touring neighborhoods, analyzing how they've developed and progressed, and all that jazz. I've spent years doing this in dozens of cities across the country so it's definitely a passion independent of my passion for real estate.

Look forward to hearing the community's thoughts, especially from the folks investing in many markets. Thanks in advance!!