Technically, you should be safe at 11 months if you just walked the reservation the day before the last night of your current reservation. Noone should be able to start a reservation (walk) unless a room is available at 8am. If you always already have a room booked for the current day as it comes available, you are set. (If you have a n night reservation, you need to walk it every n-1 days.) The problem with the booking fiasco in late April, was all the sudden more people had walks going, than there were rooms available. So, for the value rooms, once they fixed the glitch and no longer allowed over booking, only 18 value studios/2BR could be booked. Even though they likely had 36 reservations in the system, at the point they fixed it, only 18 members could have April 1/2 booked. So, the longest walks survived. There is never a guaranteed "safe" number for when glitches happen, but "the longer the better". Having 7 nights and walking at 8AM sharp every day is the safest, but should not be needed unless there is an IT error.