Walking, which is something that mainly works at 11-months out, not 7 works like this:
Today is June 12, 2021. Someone actually wants a room for June 1 to 7, 2022. They go online today and see they can reserve the room for May 12 to 18, at exactly 11-months out from May 12. Since the particular room is full through the night of May 17, no one else attempting an 11-month out reservation between June 12 and 17 will be able to get the same room for any nights from May 12 to 17, and they also will not be able to get any nights in that same room after May 17, since you cannot get any room for nights after the 11-month window starts unless you can get the beginning date.
The member then "walks" the reservation by modifying it at least every 5 days to drop nights at the beginning and add them to the end, e.g., on June 17, the member changes the reservation to May 17-23, on June 22, he changes it to May 22-May 28, and then continues that process of modifications until he eventually has the actual date he wants, June 1 to 7,2022.
Walking has a high risk of failure if attempting it with the 7-month window because nothing prevents an owner of the applicable resort from reserving nights you may actually want before you can do so at 7-months out. There are times when walking at 7-months out might succeed but that is usually only for very short walks, lowering the risk of owners reserving the room, e.g., sometimes there are room openings showing shortly before 7-months out that will actually disappear before 7-months out. Example, suppose you want July 2-6 at 7 months out. In the past, such as at BLT, lake view rooms have often been open at 7 months out for the period June 30 to July 6. However, beginning 7-months out from July 1 they are shown as filled, That is because 7-months out from June 30 was the last time anyone could actually get July 4 time. Thus, you may attempt walking a reservation beginning 7-months out from June 30 to get the actual July 4 time you want.
At Aul there are some times when you see a room category filled the date that is exactly 7-months out, as are the days before that, but rooms are shown as open 7-months plus 1 day out, as are the days thereafter. Then, each day as a new 7-month window opens,, the room disappears for that day almost instantly at 8 a.m. in the morning. The cause of that is not walking. What is happening is that the applicable rooms are almost completely filled for any of those upcoming days. They are being shown as open simply because the total check-outs for that next day exceed the total already shown as checking-in. Thus, the pattern follows that each given day disappears at exactly 7-months out almost instantly at 8 a.m.