Engineers must be expensive these days, as keeping a fleet of 3 Learjets ( & assumedly "some" crew even if a lot is SBY cover ) costs too.
Taking my cynical cap off, it is/was a novel solution to having engineering cover (to the quality you require) at 70+ bases, and no doubt saves a fortune on spares holding too.
Do RYR carry spare wheels in the hold these days, or is my memory failing me (not unlikely, but I remember someone I flew with used to routinely do so )