Even when I have volunteered at the gate never needed. It's come to the point where I've stopped because of the hassle of boarding late and finding room near by me for my bag. Those offers on the app are a total joke. You get to the gate at T-45 and 10 standbys have already cleared. I would imagine real bumps are on popular routes at popular times (think flights to Hawaii in winter) where people are going to show up. But even that seems very minimal. AA seems to have heavily invested algos to the point of overselling but where AA doesn't have to actually pay out a bump compensation.