AA has an available hold on award tickets of 120 hours. At the end of the period, it there is still award availability, you can cancel your held inventory and re-hold it. If there isn't, they would like you to do your business or get off the pot. It doesn't seem unreasonable to me - whatever "free change" period they might put in, there would be someone with a change of plans slightly after the free change period expired. If you aren't going to take an award flight, tying up the award inventory for a very long period of time appears piggish.

If there is a policy of free cancellations for paid tickets within 24 hours, this is the first time I have seen that policy referred to on this board. If it is true, I'm certain we will have a number of other members cite it quite soon (we have a lot of members, and each one flies AA a lot.