My suggestion, if it pays for itself, leave it alone, twenty years from now you have a paid off property that will be a cash cow.

Well there is ALWAYS inventory.I think that there is a lack of quality inventory at prices that are even close to being in the ballpark of something that will work.Sellers feel the market is still roaring and have things priced that way, and often get it so no reason to really pull back in a lot of places.  

How does one investor collect payment from more than twenty rental properties in a day?

At times I think of waiting until my mid twenties and other times I think....Why not now?

We are in our mid twenties with no kids and are looking to perhaps be a little more aggressive with our money.

If he's successful he plans on adding up to twenty.

Our regular water pressure is nothing to write home about.I can imagine spending twenty minutes in a bath.

Those that I met seemed to be a bit more helpful when I was in my twenties, so if you're a young one starting out, you'll have an advantage, just don't be pitiful and needy and be as professional and honest as you can be.Again, Ned and others implied, don't bug them.

For twenty of those years, I wore the hat of a NYC police officer (retired). 

Many of our inner-city neighborhoods have been undergoing sustained gentrification for over twenty years, and since 2007, we've seen redevelopment spill out into the adjoining neighborhoods in a big way.