Commissioning a new vessel

[TyersFan]

I see from the voyages of Captain Tyers that he occasionally took Brocklebank's ships on their maiden voyages. These were usually to the east coast of the USA and/or Canada, rather than the Far east route they were intended for. Was this job given to experienced Masters to pick up any problems? Or was it simply whichever Master happened to be available? Again, was there any rhyme or reason as to whether the Master would or would not stay with a particular ship?
Finally, one of Captain T's voyages seemed to keep him at sea from December 1923 to October 1924 or possibly even November. Was this usual? And after any voyage of five or six months, how much leave might be granted? He was a married man with children - marriages must have come under terrible strain in these circumstances.
Would anyone care to enlighten me?