Cadet programmes been used very successfully in UK for many years. Required as no large experienced GA or Military source available to the airlines.
Needs high quality selection and Flight Schools.
Following rigid selection criteria, 200+ hrs at flying training school, with CPL/IR and multi rating at end. ( ATPL exams passed and issue when hours acquired later)
In my UK airline cadets then went straight into RHS B737/A320/B757 after normal TR course.
RHS Base Training as required, followed by at least 50 route sectors with Training Capt. When released to normal 2 crew Line flying, rostered with Capts of at least a year experience for the first six months, on multi sector European routes.
Very successful and no flight safety issues. Many of the early cadets now retired or Capts on A380 and all wide body types.