Knocking on doors, sending out 1000s of postcards every week, 3 or 4 virtual assistants, CRM system in place for your 4 or 5 in person employees.

Postcards or mailers, or both?

We have been in this business for many years and know and tried most of the standard strategies employed to get new doors: Google Ads, mail campaigns (letters or postcards), targeted lists, etc.

He told me he keeps getting letters and postcards (of course) but that he's got a friend who keeps bothering him telling him he wants the duplex.

Currently, I am doing a lot of cold calls, postcards, emailing, etc. to lead lists and it is a lot of work even with a VA team.

There are so many wanna be MF real estate investors now they are probably getting calls like these 3-5 times per week from professional deal hunters and a couple dozen "I Buy Apartment" postcards per month.You need to STAND OUT from the rest of your competition.  

I sent a bunch of postcards using realeflow in hopes getting someone willing to sell there property.

I ordered postcards that are a little small for EDDM standards. 

For example i am looking into cold calling, RVM, SMS, & postcards and i have seen/heard stories of people being sued using some of these methods.

Skip the middleman.You have already figured out what makes a deal, what a decent neighborhood looks like, now just figure out who you have to send some postcards to.