As a DVC member who has also worked room assignement at WL/VWL and OKW (BC too, but pre-DVC)... It is as Daitcher said. It depends on the resort.
At VWL we did not use Room Ready, we used the first booked first blocked (Basically you run the report based on the reservation booking date and time and block request that way, so it was first booked first blocked). At OKW it was room ready (unless you had something guaranteed, a medical need or you were traveling with another reservation.) I personally liked the first booked first blocked method because you were atcually blocking requests (there seemed to be less issues that way) but they are 2 totally seperate hotels with different needs... At VWL people tend to make simple requests like smoking or non and perhaps a pool view (since most rooms are woods view and nothing is near the lobby, since that is in WL not the Villas). That makes it much easier to block requests since they are simple and there are many room options that could fufill them. At OKW the requests tend to be very specific and usually the same as many others checking in that day so it is harder to pre-block them...you leave the basic request and get the near hospitality house, ground floor (since there are not elevators...or request for a bldg with the elevator)...it just makes it harder.
Again, I personally like the first booked first blocked, from both stand points. As a member because I know that even though I may be waiting until 4pm for a room, it is a room that I want. And from a R/A stand point because I know that you are getting what you want. And if you didn't it is much easier to explain (and understand) that the reason your request was not fufilled was because you booked your reservation 3 months ago and unfortunatley someone who booked 11 months ago requested the same thing rather than sorry you arrived to late and get the left overs...
Sorry, tangent...not sure about the properties that I have not worked at, but I do know that OKW does rooms ready and VWL does not and that is based on the hotels preferences for many different reasons.