Is there any value in making a cash reservation for peak season travel to hold a room, then cancel it to free up a room with the intention of immediately replacing it with a rewards stay (IHG credit card free night stay not yet credited to account)? Or are the free nights stays limited to a certain pot and when they are gone, they are gone?

Also, will IHG change a points reservation to a free night cert reservation, refunding the points? Assuming in this case the hotel is full or shows no reward stays remaining so direct booking not possible.