Walking: assume you want Christmas week, Dec 25 to Jan 1. On Jan 19, you reserve Dec 19-26 capturing the night of Dec 25 and thus the first night you really want; on Jan 20, you call and drop Dec 19 and add night of Dec 26 so reservation is now Dec 20-27 (with any reservation you can drop days at the beginning and add days at the end without cancelling the rest of the reservation); on Jan 21, you call and drop Dec 20 and add night of Dec 27 so reservation is now Dec 21-28; you can continue to do that daily until you have Dec 25-Jan 1. So what is happening is that you will be getting the nights you want before those who simply use the 11 month window by calling Jan 25.
Walking really does not work very well at 7 months out because owners of the resort could have blocked out some or most of the days you want even before you begin to walk, e.g., in the above example, if you actually call May 19 for Dec 19 to 26, you are likely to find for many things that Dec 23 through night of Dec 25 are already gone.
Walking at the 11 month period is usually unnecessary but it is something to consider for AKV concierge year round, although even then you may have troubles, e.g., the days you are trying to walk through may themselves be gone when you make your first call to try to start a walk. As to other rooms and resorts generally, it is not likely needed except for possibly the following: AKV value and BLT standard for days right around Thanksgiving, first week Dec and Christmas time (Dec 23 to Jan 2); add to that possibly BCV and BWV standard and boardwalk view if your intent is to arrive late Dec after Christmas and you want Dec 31.