I don’t know if that is common timeframe for Odfjell, or any other shipping company these days, but to be Master after 13 years from Cadet is not that unusual
It is theoretically possible to become Master after 6 years, at age 25:
Starting out at 18, first with 2 years at Maritime School (STCW requirement) + 1 year Cadet + 3 years seatime as Jr. Mate + 1 yr. Ch.Mate. (Not much time for holidays)
I did it in 12 year; from Deckboy at 15 (1959) to Master at 27 years of age (1971).
PS> That incl. compulsory 3 years seatime before starting school at 18, 3 year at Maritime School +15 months compulsory National Service in the Navy.