So not a SK question at all, but a DY question!

I also have had no problem in dropping the last segment when necessary: the usual comment has been an apology for not being able to refund the remaining ticket. My impression is that hidden-city ticketing is much less of a problem here than in the States, as most tickets tend to be priced segment by segment, at least DOM-INT tikets from the provinces, where they seem to add a fixed amount to the ex-Oslo fare if one travels from via Oslo, meaning that one doesn't save money when dropping a segment.

Actually when booking a through fare on DY they add a connecting fee: "Tillegg for gjennomgående billett 300 NOK"