[dwaite]

I had a family trip where it was suddenly required I show up two hours earlier, and the original airline didn't have a flight that would get me there.

I booked a one way ticket on another to make it work, then was surprised when I tried to return home that I no longer had a valid ticket for the first.

Of course, they'll helpfully offer to let you buy a one-way ticket at the counter, 90 minutes before departure, at maximal pricing.