Fun fact, they probably profit until X-5.This model is literally used in every industry and works almost every time to have someone buy a product/service and be happy about it. 

Basically, rinse and repeat this model and leave may be 10-15% of money in the deal instead of typical 25% down for investment properties.

I think those areas are not particularly the place to start.IMO I would use the models provided by BP, and find a nice base hit, ie a nice property that has a solid but not super return. 

My financial models show 15% cash on cash return on a $950K investment for 65% of the equity. 

As a newbie investor I formed my business model around utilizing Hard/Asset based lending.

I have built my business model around the concept of paying off properties and snowballing them into more.

As for % of equity, it depends a bit on your business model.

[But is that a sustainable model, the more doors you buy?]

In addition to the points others have made, I  buy with cash and self manage because:You obviously don't pay interest and origination fees, but you also aren't forced to buy property insurance, flood insurance, insurance, insurance.... you get my pointYou don't have to let a bank get all up in your business model, sign on endless fine print, and agree to pay them for decadesno one dictates what you need do or not do (possible exception - the IRS).A sole proprietor with an all cash position and self management.

The returns are low but more than $0 with idle cash.If the market does not turn, or it turns less than $20, or takes many years to turn, returns can be okay to excellent.It's hard to invest into a hot market, model assumptions that include a correction, get excited about a 6-12% IRR and pull the trigger...many hold cash instead at a 0% return.