There are some exceptions, but they are rare, they have access to funds, and they typically built their empire when the timing was right and got lucky.Likewise, it's not often that you can buy a house and sell it for big money six months later.

At least in terms of rent, college students are paying 1100 - 1600 to rent by the room.

I’m trying to find out how turn overs are on mid term rentals and how quickly a renter can get back in your unit. 

No matter where you choose to move, you are perfectly set up (if the money works) to house hack with your wife in one unit of a two-family and then to mid-term rent the other unit because of your medical connections.

It's a long term investment, not a quick ROI.

After 2 Duplexes ($80,000), we left with $320,000 so we want to buy another 2 Duplexes (same price) with 25% down payment ($112,500/each) since we are not living there for long-term rental which left us with $95,000 left.

This last term refers to the presence of at least one child under 18 years old, and also protects prospects and tenants who are pregnant or in the process of adopting a child.

Quote from @Noah Bacon: Guru Programs are notoriously difficult to assess in terms of quality or outcome for their students.

I typically get quotes from multiple lenders.

It is your only leverage to ensure the tenant complies with the terms of the lease.