I flew JHB-CT late Jan after arriving on QF63 (on time) and it was a full flight. Return CPT-JHB was on a brand new A350 (very impressive plane) last week to connect to QF64. This 2pm flight was very empty, however the crew were very attentive and friendly. Interestingly, the Captain's welcome message included a solemn thank you for flying with them, which we commented on at the time.
OOI, this route is one of the busiest internationally (Top 25 with 4.5Mill pax in 2018 - Thanks Wikipedia). In comparison, SYD-MELB is 3rd with more than double those passenger numbers.