Megan, there was a novel by Neville Shute concerning a passenger airliner captain, The Rainbow and the Rose. He talks of the Captain responsibilities to his crew which IIRC included a navigator, engineer and radio operator and stewardess. While this is only part of the story it relates to long range, multi-stage flights without the benefit of slip crews.
Remember speeds were slow, flight times long and turn round times long too. I recall Flight (International) in the 60s recording the record annual aircraft utilization. The aircraft was a BEA Viscount achieving 3,600 hrs. This was exceptional then and I suspect routine now.