However if you are flexible and bear that in mind and are very happy with the price, I dare say you don't really have anything to lose!
Well actually, might you have something to gain? Many people book a number of flights to the same place (if they have property / relatives / time share), usually on the basis that they only have to take, say, half of them, to be much better off than booking closer to the date and paying more, but knowing you will take the flight.
If you booked 3 flights for S13 and then schedules changed on 2 of them, are you not entitled to a full refund if the times change? Not sure what the window is though to claim such a refund? Anyone got the small print on that?