I could never fathom it became regularly acceptable to roster Crews both Flight Deck and Cabin, to operate London to say Los Angeles, Joburg or Cape Town and reckon it was quite OK to assume a Crew was 'rested' enough after just one night Hotac at the Destination, then to operate the flight back the next day to London overnight.
It once was at least 2-3 days Rest at Destination on flights of that length, now 24 hours or less, seems the norm...