He was purely a word-of-mouth discovery.

I used to thought that the people and topics are purely US-based.

Gurus play on the uneducated, uninformed, naive and those desperate to make money, they are con artists, pure and simple!

Not schemy, demanding, critical, or preachy.The responses are pure gold. 

Some people what section 8 housing, some people want pure appreciate and zero cash flow, some people want all cash flow.

We have done well investing in 0-5% in personal homes and than saving the rest of the down payment for the 20-25% pure investments.

We used the profit from the house and our savings to than supplement that with pure rentals to grow our houses quicker.

Are there factors within my control or specific to my situation that influence this, or is it purely based on lender policy?

Weather or not you put 20% down to avoid PMI is purely a math personal decision that you have to make. there will be some folks that tell you 20% down is better and others that tell you go as low as you can.  

From a pure financial standpoint, assuming all houses cash flow well, it is better to have 5 houses than one.