There are definitely more discount inventory buckets available close to departure. About a week and a half I ago I had to book a last-minute ticket home to SEA from ORD because of a family emergency. My travel agent booked me on the next available flight (8am the next morning when it was after 6pm CT) and it booked into Q. My ticket was actually slightly cheaper than the 10-day advance so the net change fee was less than $150. I was, uh, surprised.
