Shortening a VOR approach in the bus requires some careful reprogramming to get the leg sequence correct and the autoflight system to behave appropriately. The majority of non-precison approaches we fly are overlays and the AFS uses a mode called Final Approach to compute a lateral and vertical path rather than raw data. The alternative is to fly it using track and flight path angle which takes a lot more monitoring. A lot of airlines have extensive training programmes and some of the trainees are very inexperienced. Throw in multi-sector days and short turnrounds and the trainer is working flat out.