QR do not give priority to fatigue related safety issues.
It is an issue that is completely and thoroughly brushed under the carpet. Our Flight Safety Department do their best within their jurisdiction, which is related to Stabilized Approaches, long landings etc. The usual things, at which they are quite good, but they have no say on rostering.
You will get called into the Safety office if you are Vapp+15 at 1000ft AGL, but the fact that you have just done three sectors after reporting at midnight Doha time (yes, it happens) is completely ignored because you were legal within 5 mins.
Someone asked about the A330 and B777. The flying time calculation for B777 has recently been changed (because of crew shortage...), so from having done max 100hrs a month, they are now doing 130 (no joke) since only time spent in the seat counts towards the flying time total. They do however get paid for the full amount.