Most specials are seasonal:
Generally the resorts offer specials during quieter time periods only. Typically in the summer or fall. Winter specials are not common, so if you see one during winter season, book it before it's gone!
Free Night Specials:
Most free night specials are repeatable. So, for example if you stay 4 nights and get your 5th night free, you can also stay 10 nights and get your 5th and 10th nights free... and so on. The longer you stay, the more free nights you can receive!
Multiple Discounts:
At times, a resort may offer more than one type of discount. However, please note that one discount can not be applied on top of another discount! When there are multiple offers from the same resort, you generally just have to pick the offer that gives you the best deal.