This seems crucial when you are in the middle of a negotiation on purchase price, possibly trying to push the price lower or knowing when to walk when the price to CoCROI gets too high. .The equation I seem to think of is this((<Purchase Price> * .01) / 2) + (<PurchasePrice> * .002).So an example of this would be:($280,000 * .01) / 2 + ($280,000 * .002)$2,800 / 2 = $1,400 + 280 = $1,680.I seem to be within $5 of every mortgage I am considering.

Take now larger pool of capital to buy a better deal or invest in two deals.In many cases, buy and hold doesn't equate to scaling fast, especially on your own.

Otherwise, it might be difficult to prove in case court comes into the equation. 

Paying off debt doesn’t always equate to making more money, so really think about that.

I rehab a lot of old houses and the material cost alone on a job like that can run 5K before labor.Overhead is always a factor when choosing a contractor but it doesn’t usually equate to s 400% increase in pricing.

Add that to the equation and it's easy to see how in a low cap market, you could realize very high returns. 

But this may be an equation of "Who not how".

I don't think tenants will  have resentment if you told them the rent they pay helps the landlord pay down the mortgage because most people on this planet, including many real estate investors, don't have a clue in regards to what that statement equates to.

I wouldn't discount that partner's capital and access to financing in the equation.

With that said, the idea of being able to help somebody hoping to retire soon avoid a big tax hit like the one that would occur with selling an asset is definitely appealing as well as, hopefully, the possibility of purchasing an already rented property and removing that stress from the equation.