Last fall I overslept and missed an 8am TPA-EWR. I arrived at the airport around 10:30am and smiled to the agent at the counter as I told her that I think I missed my 8am flight. She laughed, spent 5 minutes typing, then handed me boarding passes (upgraded no less) TPA-IAH-DTW (rather than TPA-EWR-DTW) and my flight was leaving in 30 minutes.