Has anyone ever tried to arrange an appointment trade - try to reschedule the appointments in synchrony so you manage to swap times?

I have one for LAX this Friday 9/9 at 245 and can't make that time (will be on a plane heading there, but won't land until 5pm)

I realize you run the risk of somebody else looking at the same time and snagging the slot of whoever cancels first, but since I know I can't make my appointment, I'd be willing to risk it for a slot some time in the next month or so that I knew I could use.