Kit Frick (kittsburgh on QT) has signed with agent Erin Harris of Folio Literary Management.
Then in one 48 hour period, I got 3 requests right in a row, and I figured I was on a roll, so I sent out 10 more queries. Suddenly I had an offer, and I followed up with all the agents who either already had my full or who I'd queried recently enough to assume they hadn't yet read my query. Then I got a flood of requests for fulls from those nudges, and 2 more offers came in during the week.
So, all this to say that I went very fast from feeling discouraged to having 3 offers. I simply hadn't queried the right agents for this book during my first couple months, even though I'd done my research. You can and should be organized and research your list carefully, but I don't think there's any precise science to querying.