Also because they focus on one strategy. 

The best strategy I seem to have deployed so far was to contact all my current tenants and let them know I’d give them a cash referral fee of $250 for anyone they recommend to me that goes through the vetting process and successfully moves in.

We've utilized the VA loan for our current home, and this strategy has worked well so far.

The "big" firms like AA may get a lot of hype but they generally can't compete on the next level tax strategies (Family office type strategies) nor customer service as their employee turnover is quite high.  

What strategies or lessons did you learn along the way?

SubTo (Subject-To) can be an excellent strategy when done right. 

Given the competitive market at the time, every property was receiving multiple offers, and securing a deal required both strategy and speed.

There are definitely areas where you could repeat a similar strategy but with even better cash flow.If you’re ever looking at growing your portfolio elsewhere, I come across off-market deals that could align with what you’re looking for.

•For your next purchase, check if you can leverage FHA financing again—it’s one of the most powerful ways to scale quickly.Resources to Learn More•Due on Sale Clause & LLC Transfers: Nolo.com•FHA Loan Rules for Multiple Properties: HUD Handbook 4000.1•Scaling from Single-Family to Multi-Family Investing: “The House Hacking Strategy” by Craig CurelopHope this helps!

There are a few strategies you might consider to accelerate things.One option is a cash-out refinance.