I think I understand your question. There is a limited number of rooms for each dicount rate (or code). So, there is no guarantee that when you call for a room you will be able to get one at the annual pass discount rate. It helps if you are flexible in what resort you want to stay at and try adjusting your dates to find a good rate.
I know from personal experience that I have called and there have been no annual pass rate at the resort I originally called for. However, when they checked other resorts there were discounts available. The same thing has happened if I change my travel dates slightly.
Hope that helps.