There is adequate rest....and there is good rest. Im sure most of us here know the difference. You are right havick, adequate rest should be a no-brainer if you have a roster. But getting 5 hours sleep (which may be adequate) before a 5am sign-on because your body wont shut off at 8pm as that was about mid-sector for most of your flying done the week before is not going to be 'good' sleep.
Its this chopping and changing week to week and in Jetstars case it seems, within the week, that causes the most of fatigue through unstable sleep cycles.
Im not an expert in the field, but have done my share of night freight and 'airline' rosters so Rondair, with respect, if you havent had to do it please keep your comments to yourself.