Tiger321,
I see what you mean. I didn't spend too much time on cathaypacific.com, but yes it seems through May, June and July the JNB service is shaved back to 5 or 6 per week. I think you have to go back to the 747 days for anything other than a daily JNB service.
However, sometimes they redeploy aircraft to more profitable routes. Paris is an example of this. It chops and changes from daily to double daily. That doesn't mean less crew usage, just means the aircraft are used elsewhere.
PS. Not good news for the Saffa commuters.