As to the mention earlier of walking 30-days, I doubt that was referring to actually continuously adding days to a 4-day reservation, which even for a renter would not make sense because if you end up with a 30-day reservation, you could not rent it to more than one person, e.g., book 30 nights and then rent 10 of them would result in the loss of the other 20 days when doing the modification to 10.
At 11-months out, the maximum number of nights you can get is 7. To actually start a walk for a reservation, you need book only 2 nights at exactly 11-months out. Example: (a) you could reserve June 3 and 4, 2026, today (July 3, 2025) and that locks in those two nights for a room because no one else can get the room already taken for June 3 and 4, and no one else can get any nights into the future for that room after June 4 until July 5, 2025. Thus, on July 4, 2025, one could drop the night of June 3, 2026 and add the night of June 5, 2026 and daily thereafter drop a day and add a day until you finally get to 11-months out from the start date you actually want, and then change the reservation to one for up to 7-nights (and if desired add days thereafter).
Moreover, even if the professional renter wants to be able to sell a reservation for more than 7 nights, e.g., possibly 14 nights, the member would not need to extend any one reservation via a walk to do that. The member could make two separate reservations, e.g., for 7 nights each with one starting the designated check-out date of the first one, using the same membership and using points for the same resort, and then just have the reservations merged into one to complete a 14-day rental.
My guess is professional renters are thus not making and then walking real long reservations but instead making multiple shorter reservations that can be merged later if needed.
Also, I note that some believe professional renters are using the LLC form of ownership. Possibly doing so may help hide that a member is doing multiple reservations via different LLCs, but the punishment if DVC could discover such a rental pattern would not require any finding of numerous such rentals. As I have noted in another thread, the POS's have always required point owners that are corporations and other businesses, which includes LLC's, to limit the use of any DVC rooms, and any recreational areas at the DVC resorts, to its principals (controlling owners or shareholders), directors, officers, and employees. Thus, any rentals, or even just reservations, to persons other than to those designated persons, are a violation of the POS. If DVC has evidence to show an LLC member has actually been doing rentals, or even any reservations, in any number, to persons that are not principals, directors, officers, or employees of the business, DVC could cancel the reservations, and require the LLCs involved to provide evidence with every future reservation which confirms the reservation is actually for someone who has the needed relationship to the LLC.