Yea, I don't think they do this as much anymore, but I'll tell you our experience.
Early Dec./2002.........so 2 1/2 years ago. My Dh and I were staying CL at WL for 2 nights and then courtyard view the Last night.(when I called, they only had the two nights available in CL)
We have our two nights on CL and we are about to move to the other room. We thought, oh, what a drag, after only two nights in this room (woods view) we have to move our stuff. so we decide to check and see what it would cost to stay and if they have availability. The guy said sure. It would be $30. We said ok. They must have had a cancellation.
And this was when we were getting an awesome discount in the first place. I think I paid something like $189 for WL CL for the first two nights. Oh, I wish I could remember. But I do remember it was a great deal. I probably wouldn't do it again, but it was nice to experience it once.