I'm not aware of massive subletting going on but in general if you sublet without letting your landlord know about it you risk losing the apartment entirely, an

I'm not aware of massive subletting going on but in general if you sublet without letting your landlord know about it you risk losing the apartment entirely, and most landlords won't let you sublet for longer than six months. Of course sometimes it does happen. A couple of friends of mine have been in the same sublet for the better part of a year but they're also looking to move to a more stable place. The renter has basically moved out but is keeping the flat around "just in case"