You'll want to check in daily or multiple times a day if you are really motivated to get on the list. They fill up quick, especially if the shoot sounds really interesting. The RRS is a quick and easy way to have all the postings sent to your email.
Our shoot at Indent was a perfect example of what metakephoto and OregonVelo are talking about. It appeared full within two Days of my original posting, but during the final days before the meet there was somewhere around a dozen cancellations and everybody who had wanted to go were able, so don't be shy about the waiting list if you aren't quick enough on the initial draw.