Understanding passive income from buy and hold RE

[Jeff Irwin]

So, in my reading, it appears that many pro level investors look for $100 per door in cash flow. So, if I am reading this correctly, and I want to set a goal of $72,000 year in passive income, that is $6000 per month. At $100 per door, I would need to acquire 60 doors.

Am I missing something?? That seems like an awful lot of properties to acquire in order to passively earn a modest income.