I am comfortable using excel to calculate the IRR, however, is that a step investors take or are they trusting cash-on-cash as a good enough ratio to know it's a good deal?

Do you believe that 191,200 is still not a good enough mark-down for a 4-Plex with an ARV of about 240,000?

Buy a fixer upper then do a refi-cash out if you can find a good enough deal.

But for some people it's worth it, especially if the deal is good enough.

A person may have to rent because their credit isn’t good enough to get a mortgage.

For example, an investor simply saying they want $200 a month in cashflow is really not good enough. 

It was a 4 bed 2 bath (it was a beautiful pig, a good enough remodel to rent but issues still remained we were blind to it at the time).

So, the area is good enough to raise children in.

If the area is good enough to own 1 rental, it is good enough to own 10.

It was good enough for Grandma and Mr Nickerson, it'll work for you. :) That will give you some first hand knowledge of analyzing deals and applying them, and if if you don't get a home run out of the gate, at least you have a nice place after the rehab to live.