I'm a little surprised, in that there seems to be some artificial limits to availability. I was told by my guide that the only limits would be that of the actual number of "standard" rooms available at the desired resort.
I tried to book my 7 night "free" stay for the end of May, and had to settle for the Poly. I was told that YC & BC, and BWI and no availability for this "offer" during my requested dates.
I'm still happy I took the free stays, instead of the $5.00 per point, put for those about ready to purchase, it's something to think about.