'Centy' am sure that was the case re Canberra Bombers being hand flown at night IMC SP but would they be doing so with the tolerances of what would be expected of today's drivers in say the ML-SY corridor @ 39K?
Also perhaps the design of the old girl thick wing lots of lift not as pitch sensitive for Eg as against today's rather delicately balanced swept wing machine was quite a bit different. I know having hand flown a LR35 at 39K was bloody hard work keeping it within +/-500ft even for short periods of time, besides as we know any Airliner experiencing equip failure in the order of no auto-flt systems means yr going down regardless to lower Alts out of RVSM airspace & a better environment for hand flying.
Personally I see no joy or real need to sustain accurate hand flying skills of a transport Cat jet at Alt,they where not designed to be reg flown like that nor are the drivers of today.
Hand flying a circuit in reasonable wx conditions is the only place to be getting any 'stick time' outside of a Sim.
Wmk2