I am noticing that when a CX F is available (at least traveling West) Y & PE are also available but there is no J available on the same flight. Once the F is gone, J seems to open up but rarely more than 1. There is a lot more F availability from the East Coast than the West Coast for my searches in the New Year.

Closer in, it also looks like they are releasing inventory up to a certain date and it will remain static for a couple of weeks and then you see new inventory; like a sliding window about 6 weeks wide.

James