When I went through the VC10 OCU as a student in 1983/4, we were given a sound and very comprehensive groundschool....
Then some new ex-Victor Stn Cdr turned up and dictated that people didn't need to know as much, so ordered the groundschool course to be shortened. Successive reviews chopped more and more out of the course, so that when I came back in 1993, the groundschool course was a bare shadow of its former self. For example, HF radio was dismissed as "It's a radio, you turn it on and dial up the frequency" - nothing at all about day/night propagation, SSB or available networks.....
We had a student who had done his AFT through the Seneca CPL/IR course at Prestwick as an experiment. In all areas of theoretical knowledge he was streets ahead of his METS colleagues......