Originally Posted by dark_horse
Had I instead turned up to the airport a few hours before travel and bought the cheapest available Y ticket (though, in practice, this may equally have been B or H; semi-flexible) a few hours before boarding, the ticket would probably [true?] have been cheaper than the equivalent FF ticket booked months before.
You are missing the obvious that if a flight sells out , you cannot buy any ticket , flexible or otherwise , so waiting until close to departure on a busy day could leave you without a flight
if you make a change on a cheaper fare, you could end up paying both a change fee plus the fare difference to a fully flexible fare as well as still having a ticket that is not fully refunable ( since original amount remains non refundable )
If a cheaper fare is refundable and changeable without a fee , then I don't buy a full fare ticket unless I needed to make a change to a flight where only the higher fare basis is availble ; e.g. for Europe-AU, I buy A class fares on EK which are fully flexible and refundable ( albeit with a EUR30 cancel fee ) rather than paying a lot extra for P
Fully flexible doesn't mean it has to be the most expensive fare offered