They tend to occur once a month...always loaded overnight Saturday into Sunday. From what I’ve observed, usually the first or second weekend of the month.

There tend to be biggèr changes seasonallly, and about 3 months out. October 7, I woke up to find major headaches with changes to two January itineraries. A month earlier, one Sunday morning I woke to minor tweaks to December itineraries. One of those Dec itineraries was purchased well in advance and had seen major changes back in March.

Here’s a great article about AA scheduling: https://crankyflier.com/2018/03/12/a...g-improvement/