I have definitely experienced the lower placement on the UG lists when I book further out and get less expensive fares. When I book my typical flights 7-12 days out, I see myself get upgraded about 60% of the time or a postion in the top 5 (non-hub to hub mid con), but if I book some travel at the rare time of about a month out or more, then I see upgrades 0% of the time and placement on the list in the teens.

On the transcons to/from SAN there are a lot of military and government, so higher fare buckets. Just in informal conversations with other 1Ks, i hear of different travel booking policies. Many of these travelers have told me they are usually booking within a week or so. Just a very small sample size though.

I think price of the ticket/fare buckets have a HUGE factor here.