Something like 10 months ago I bought refundable business class tickets for SFO-PTY-LIM, one-way in July, for about $2,500 per. Then, about three months ago, I saw the same OW route available for half that price, but nonrefundable. I canceled the refundable tickets and bought the nonrefundable ones.

I have no idea if my experience is a common one, but there’s another data point.