I'd say that AA (and probably other airlines) have anomalies when it comes to this. Example: I was in LGA headed to I forget where, and there was a nearby flight to ORD that was oversold and they were offering a $300 voucher to take the next flight which would depart in less than an hour after the oversold one. Recently, I was in ORD at the Eagle concourse and a nearby ORD-ICT flight was oversold. They were offering a $200 voucher for a flight that would depart over 5 hours later. Where's the logic there? I suspect it has something to do with the first case being AA versus the second case being AE, but still. There's no balance in supply and demand there. In the LGA-ORD case, I'd think that there were plenty people volunteering for this but in the ORD-ICT case, they'd probably be hard pressed to find someone.