"It is in the week before travel that Southwest's fares tend to undercut competitors." - NSX
My experience with Southwest is totally different. I always book my travel within a few days of departure. And, I always shop around. Southwest is never cheaper. I feel like I can honestly say never because I have not flown with them in years due to this. I know it varies by airports. For me, Southwest has long since ceased to be a low cost airline. Too bad because I used to use the nonstops all the time. Now, I get to go through ATL!