There's no precise figure because no one will understand your STR or market as well as you do- or, as well as you will (with time).

You don't need to know everything to get started; you need a foundation to build on, and the rest will come through experience and then refining your education.You can build a basic understanding of investing in 3-6 months.

I am hoping to learn more about how investors analyze their deals and make decisions, as well as looking to better understand general real estate investing.

I don’t understand how this isn’t a clear-cut case.

Whichever direction you go, be sure to work with folks who understand this and gives you the confidence to take reasonable action - I'd personally take an okay investment and weather the storm for a few years that will eventually perform well, and do that each year - rather than take 3 years to wait for the best deal possible.

I'm trying to understand how frequent this is.  

Best way to understand this is research appraisal standards and means. 

I don't know the Baltimore market but have a friend who is a very savvy investor there and maybe he would do some coaching to help you understand which way is up.

Their program is simple to understand for the most part.

This is something I aim to understand more about.