I am just going to reiterate what others have said: The waitlist system will automatically snap up rooms as the waitlists are filled, but it doesn't confirm the reservations themselves. The process works like this:
1) A customer cancels their reservation and puts a room in to availability
2) At some point (either immediately after Step 1 or several times a day...nobody know which) the system will check for waitlist availability for those rooms that were released.
3) If a matching waitlist is found, it holds the room and puts the held room and wait list into a queue for a Member Services person to process.
At this point, the room is held, but the reservation does not appear in the member's dashboard and still shows as a wait list.
4) When Member Services can get around to it, the queue is processed by a person. The person who processes it will check for things like borrowing points, having enough points, cancelling existing reservations that the waitlist might replace, etc...and book the reservation. This process may take a few days as it's a manual process.
After Step 4 is when you see the actual reservation online and waitlist fulfillment email. I think most people are checking availability between steps 3 and 4 and finding ANOTHER available room to book. There is a slight chance that folks are catching the room between steps 1 and 2, but I think that is going to be Rare...if it's even possible at all.
Me philosophy on it: There is no harm in continuing to check availability, even while you have a wait list. Personally, I doubt it's necessary, but it doesn't hurt anything to check and book the room you want by hand if you find it.
I've had tremendous success with waitlists as long as I wasn't wait listing exceptionally difficult to get rooms. Club level, Board walk view, MK View at BLT, Grand Villas, standard/cheap views, etc...can all be difficult to book. Pretty much every time I've booked easy to get rooms (Lake Views, SSR, OKW, AKV Savannah view, etc.) it's almost always successful.