How did you buy your second investment property?

[Thomas W.]

A lot of people talk about how they got the downpayment for their first property, whether it was by saving their money, working with an HML, getting it from friends and family, but once you get your first rental property and it's cash flowing say, $500/month where do you get the cash for a downpayment on your next property.

By my math, even a good cash flowing property that's getting it's mortgage paid down would still take 2-3 years until you could refinance for a down payment on a second property. Is there something I'm missing when I hear about people buying "6 investment properties in one year"?