I saw J fares are cheaper when booked as a round trip compared to 2 one-ways. My question is what happens if the return leg needs to be changed. How does AA value the return leg compared to the entire flight? Is there a time frame limitation for how far into the future you can modify/book the return leg? I am not sure if it is better just booking two one ways and eating the extra cost, especially if I need to adjust the return date. Thanks!

I am a little new to AA since I am more familiar with Southwest's policies which just considers a round trip the same as two one-ways.