It works a lot faster than you might think. Sure, if you're setting up a new site in San Francisco or Austin this kind of thing will be a much harder sell. But in small-town USA where no one knows what SEO means, it's actually really fast.
We've had people jump to #1, #2, and #3, of target keywords in under a week (we don't advertise this, btw, because it's unrealistic), but 30-45 days is very common.
There are millions of businesses in markets less than 25k people, and those people are our targets.