I think CRS just make it up as they go. Used to be that you could get a STBY on your last Rday but now you need 2 days and #2 day can't be a anticipated 1-in-7.

A couple months ago or so, I was 1 or 2 leveled under the first flys and was telling buddy, how I was gonna get an easy Sat morning STBY(because that was all in open time); well, they gave the STBYs to the first flys and I end up with that crappy YMX (short layover)-EWR (hub turn)- MEM trip!