Straight through training
I went straight through on the JP and there was certainly a relatively large chop rate, but now too long ago to confirm whether my course at Syerston reached or exceeded that level.
However, I do recall that a proportion of graduates from initial office training at South Cerney were sent to get time on the Chipmunk before going on to the JP. Either it was part of a random trial or, I guess, because of marginal results in the aptitude tests.