Additionally, I would like to attempt to do the process Owner/Builder with subcontracting work out as well as doing some of the work I'm comfortable with (I have some experience with bathroom & kitchen remodeling an am not new to the construction industry).

I have a commercial property with four retail spaces and three different businesses.

Left me feeling like a basically have a retail/fulfillment person on my team so I'm a big fan and would recommend giving them a shot, especially if you're in a similar position as I was: Needing to furnish an STR quickly and cost-efficiently. 

I am also really interested in the stock market and the real estate industry! 

Is anyone familiar with the rule listed in the title and is anyone that has a full-time job in another industry using this rule?

Typically by the time it reaches the MLS, it is listed at retail value, and you're not going to get a screaming deal, although there are those diamonds in the rough and my team frequently does "fixer" deals off the MLS.

Quote from @Joy Daniels: As a short-term property manager I've seen how this industry changes so often—new guest trends, tech tools, and regulations seem to pop up all the time.

Thanks in advance.This is standard practice in the industry.

We did quite well in the Timber game in the 90s Owned many thousands of acres of Timberland during that time its a great industry one of the favorite things I ever did beat the heck out of rental houses LOL

I am not an expert here but my thought is that you would learn a lot by getting your license and have more credibility in the industry at large so if your time and finances allow- get that license:)