A weird pattern, but I have noticed that when AA loads a schedule or aircraft change, they sometimes temporarily dump space, perhaps by accident. For example, there was a 24-hour period late-last year when they (re)upgraded the LAX-LHR aircraft on AA108/109 to the 77W (re-adding a First cabin to this flight). At this time, the entire F cabin was available at the MileSaaver rate, and on every day in the calendar after the upgrade schedule. The space was there for c. 24 hours, and tickets ticketed; my partner and I booked 2 MileSaaver seats in F for July. The same thing happened to us a year prior, when AA dumped J seats after downgrading the aircraft on this flight. Coincidentally, in 2016 we were travelling from LHR to LAX for our wedding, around the time AA added a second daily flight, they again dumped all the F space for about 24-hours as flights loaded (we held 4 F seats on one flight so our family could all go together, but eventually cancelled as we travelled on different dates and the space disappeared). I've noticed that changes like this seem to create a window of dumping space. It's a once a year unicorn moment - so long as they keep changing their aircraft or schedules - but if you're obsessively consistent in checking (which, of course, you should not have do do) and you begin planning the day the flights open (again, they can do better here), you can sometimes get something on a west coast nonstop in J or F if the conditions are right. In our last booking, we were planning 330 days in advance (a luxury I know, but it's for a sibling wedding so dates were set) I also noticed loads of flights with at least 2 J on DFW-LHR flights.