I've been a little slow to respond and I apologize. 

Or slow Do people actually rent single family homes for $4000 ?   

You'll have them paid off by the time you retire and will enjoy a significant boost to your retirement income.Generally, you want to grow your portfolio wide (more units), before you go deep (paying off).

Despite having delivered over 480 investment properties, we always seek the opinion of a property manager for each property before considering it.This deep dive is very impressive.

Progress is slow, because amongst all my properties it's the furthest away and between a full time job and landlording, I can only work on this property on weekends.I have completed re-framing, re-plumbing of drains and supply lines and new electrical rough ins, but property has no finished walls, ceilings, or flooring. 

Deep value add multifamily project. 4 units. 2 x 2 bd 1 bth, 2 x 1 bd 1 bth.

The city can be super slow to approve permits and it being in a historic district could make it drag even longer.

For example: A 10 wide x 20 deep x 8 tall unit, with studs, roll up door and doorjambs; is really 9 wide x 19 ft 6 inch deep x 7 ½ foot tall.

Learned how to dig deep and just keep pushing forward till the job is done Did you work with any real estate professionals (agents, lenders, etc.) that you'd recommend to others?

I think for most advanced company (such as Pfizer vs JohnsonNJohnson), their future lies in how much deep research or drug product they can find through AI.