50% success for PHX-JFK for DM is about right, particularly on lower fares. It is still higher than for PHX-ATL where my success rate is much less than half regardless the day or fare I use. In my experience, it does not matter all that much when one flies... I think there are a lot of last-minute paid upgrades happening. Good for Delta, I guess, although their policies have led me to give them a lot less money now than I used to until last year, so in the end their FCM policy probably is a wash for them if that.