Due to the hills and runway profile, S-turns are a standard procedure for landing at the Zar Mountain Gliding Center, Sebastian Kawa's home place. Also, they are commonly taught in Poland as just ONE of the methods to lose height in a particular situation. The more methods you have at hand, the better. S-turns allow you to do both: descend and yet delay landing a little bit, if needed, e.g. to give time to clear the runway.

Tom BravoMike