In the case of the cabin crew they flew both 707 and VC10 known on introduction of the 747 Jumbo as Mini fleet.
There were a number of 'non-integrated stations' which meant cabin crew could not switch aircraft types. I can't remember which ones but it it did lead to a lot of very interesting slip patterns!
The plum VC10 trip was Sydney through the West. LHR-JFK-LAX-HNL-Fiji (can't remember 3 letter code) SYD. Then either back the same way or through the East including CMB-BAH. 21 days unless tech or scheduling problems then think of a number.