This lead me to Grant Cardone, BiggerPockets, and majoring in Finance with a Concentration in Real Estate.

I personally concentrate my investment efforts in the Columbus area and my team and I have a network of property managers, general contractors, and lenders etc. that I strongly recommend.

I'm concentrating on brrr investing on small multifamily and value add small apartments for now. 

It was starting to get a bit overwhelming to determine where next (and whether all or to ideally concentrate within a few). 

I'm curious why you just want to concentrate on Absentee Owners.

Are there any problems with concentrating on too large or too small an area?

I would concentrate on getting yourself ready to look for and land your property!

The best way to achieve this goal is to buy a property that attracts a tenant segment with a high concentration of reliable tenants.You can identify a segment with a high concentration of reliable tenants through property manager interviews.

I am a part time investor with a concentration in Kissimmee, Lake Wales and Sebring.I own 5 rental properties and manage another 8 more for family. 

I would concentrate on hud homes that are under priced ,Mthe ones you can add value to by doing a light rehab , I'm in central Florida area myself and I just saw a 3/3 cbs ( concrete block stucco ) 2400sqft SFH on 3acres just get bought a little less than  2 months ago for 51k that just needed updating , the buyers only put in contractor grade carpeting and replaced a few light fixtures and put it back on the market for $93,500 , they didn't even replace the blue tubs and sinks in the bathrooms and it didn't have a oven just a stove top .