Buy cash vs leverage - is my plan any good?

[Account Closed]

Hello and happy Friday!!

I'm looking into where to put some cash and I like the idea of buying something cash and renting it out. The theory is that I can have fewer properties to manage and less debt than leveraging, hoping that I can get good ROI and get to financial freedom with 3-4 fully paid off rental properties within 6/7 years, each mortgage free property helping to finance the next one.

So say I can save 3k per month from the day job. My primary residence is mortgaged at around 2k per month but I can buy one additional property outright now.

Now:

3k per month from rental #1, 3k per month from savings - pump that into my primary mortgage and I can have that paid off in 4 years.

In 4 years:

Buy another rental (#2) with a mortgage and rent it out.

2.5k per month from rental #1, 3k per month from savings, 2k per month from not having primary mortgage anymore . 2.5k per month from rental #2 - thats 10k per month you can pump into payments at that rate you could also pay off in 3 years (10 year mortgage of 350k at 4.25% is about 3500 and you are making an extra 6500 per month in payments bringing it down to 3 years)

So in 7 years I have 5k per month income and I have a mortgage free primary residence, right? That seems simpler than trying to scrape together a couple hundred dollars a month from a whole bunch of properties to get to the thousands of dollars per month I want coming in. 

And a bonus question... am I being unrealistic to look for a market with 15% ROI on a mortgage free STR? Should I aim for more like 10%.

Double bonus question -- WHERE can I get 15% ROI on a mortgage free STR??