I was looking for a low price on a flight for my college-aged daughter from the US/Boston to Brazil. I found a great deal, and want to share the strategy I used.
As an even bigger bonus, I then discovered that I was able to "upgrade" to the Comfort+ seats on the international leg of the trip for $109. extra each way. This gives 4 extra inches of legroom, and more recline. This flight is for my very tall daughter, and since the flight is 10.5 hours, I splurged. She will be kicking in some $ for the flight, but the upgrade will be a Christmas present. I've checked a few more times, and have not seen this deal again. In the future I will be using this strategy, 'cause you never know!
I hope that this strategy helps someone else!