Ok so maybe when you're dealing with over one hundred airframes it is possible to imagine a few situations where the MEL gives no joy.
How did you get the aircraft back from the outports?
As I said (several times) I don't know anything about Qantas, so will NOT comment on your hundreds of airframes.
Most of the situations I have been involved with and was referring to (both about fixing them and also ridiculous hours on duty) were Overseas where we only had the one airframe, IF we couldn't fix it or get around a problem, it didn't operate until it was fixed. We had no what you call PEs on site or even in the Countries involved.
On a few occassions we had outside help, from other Airlines, or people from Airbus one time with a major problem in Canada, but most of the time you just have to get by.