Some folks have figured out a way to do this w/out the daily calls (you can't do it online because you have to drop and add ad day at the beginning and a day at the end), but I've never been able to quite get my head around that...
Good luck!
See if this makes it easier to understand...
It's not effective at all at 7 months because an owner at that resort could swoop in any day to book the days out from when your walking reservation ends and your real dates begin. That's because for resort owners, they are already within their booking period and don't have to wait for the first day of what the need to be available.
But at 11 months, you can't lose the room until the 11 month window opens for a day outside your walking reservation.
Say there are only two rooms available, like at VGC where there are only 2 GVs. You want a GV for 7 nights (lucky you to have that many points!) and you own at VGC.
Your dates are Dec 8-14. So you start walking the reservation by booking Dec 2-8 by calling Jan 2.
Now someone else calls the next day and books Dec 3-9.
Then I call on Jan 4. I want Dec 4-10. Guess what? I can't book because the FIRST day, Dec 4, is taken by you and the second person. So while I can see the dates at the end of my desired stay are open, the FIRST day isn't so I can't book anything. Not until the 11 months opens on Jan 8, when your walking reservation ends. That is, unless YOU walk it and extend your dates.
Those first two people who book are in total control of the GVs at VGC until they finish walking, if they do it right.
And even there was no second person, just you and me, it would still be true. Again, at VGC one of the GVs is HA. YOU book that one as above. When I call Jan 4 and I request it, I can't get it because you have the first days locked and they are unavailable. W/o the first day open, I have to wait until the day it IS open to be able to make that reservation.
It works with only 2 rooms; it works with many rooms. That's why people walk. By booking and locking up the FIRST days, no one else can book that room until there's an opening. It's not as obvious with most resorts, but believe me, I own and walk at VGC, and in fact did just this with a GV for next Feb.
You don't need to call each day. Only toward the end of your walking days. Just cancel and extend then because only you can control that room at 11 months plus 1 day.