However, the people who use rules of thumb don't have sophisticated software that can analyze deeply thousands of potential deals every day!

I have exact the same situation as Chris, I bought the properties from CR of Maryland, and I lost of ten of thousands dollars and their property management team are a really big mess and incompetent, it feels much better after switch to RPM. 

One mistake or big unexpected expense could ruin you if you only have one or two rentals that are not cash flowing.That said, especially in the current environment, if you are coming from a very strong financial position then there may be times where it may fit your goals to invest in a highly appreciating area with no or negative cash flow.

A good real estate accountant can save you thousands of dollars by leveraging entity selection and formation, tax deductions, cost segregations, bonus depreciation and tax planning.I recommend finding an accountant who specializes in real estate taxation, business taxation, financial planning and tax planning.You may want to consider working with your accountant remotely to expand your options.I would also recommend looking for a accountant willing to work with you throughout the year.

He was just an unemployed alcoholic living off the government teat, ruining one rental after another.Smells like money.

Just for numbers sake, there are some YouTubers doing 10,000 calls, 10s of thousands text messages and 10,000 mailers a month.

You'll end up with a dog that you can't unload at the end of the day when you've dumped thousands of dollars into it with no positive return. 

It's one thing to say that "a typical tenant would likely stay for X years" and another to say that "on average, across our properties and thousands of leases, we see that tenants stay X years" -- the first one is a bit of an assumption and the second one is a stated fact. 

They billed me $200 plus thousands of dollars. $2 was only down payment...

This has saved me hundreds of thousands of dollars.