Question : How long do most people stay in Salzburg when they fly in from Madrid?
Answer : Of course you're not most people, but if you were, you'd stay roughly six days.
Question : If your plans are flexible, have you considered changing your departure day?
Answer : In December, Sunday is your lowest-cost day to fly. Being flexible with your travel days garners you even more savings during your booking.
Question : Are prices changing frequently for this route?
Answer : Prices for MAD to SZG do change a lot more than most routes. The further out you book a route, the more likely you are to save.