Is 2% rule valid

[Murray Twyman]

I am new to real estate investing, and I have come across the 2% rule. I understand it is much like a litmus test for cash flow and is simply back of the envelope math. However, it seems there is rarely anything that comes close to this rule. So I have a few questions.

1. Is the 2% rule valid in today's market?

2. Is the 2% rule a way to quickly eliminate 95% of property investments allowing one to look at only a handful of deals?

3. Is the 2% rule an upper bound for a range of values? For example, a house's rent should fall between 1%-2% with 1% being a strong "no" and a 2% being a strong "yes".

also sorry if this is the wrong place for this question I am new to the forum.

EDIT: these questions came up after reading Brandon Turners book