The 2% rule yet again - parameter seems incorrect

[JJ Cole]

I have the read the 2% rule as the rent should be 2% of the purchase price. Wouldn't be more apt to frame this % rule in terms of the mortgage on the property?

One could put 25% down instead of 0% down and cash flow that same on a property with less than 2% rent - purchase price ratio (of course your cash return would be lower). So my question is -- is there a % rule that relates month rent to total mortgage loan amount? I am looking to find this since I need to cash out refi 6 props that I bought cash. Thanks in advance.