Without being too specific. The Air Law exam is too focussed on the bureacracy, too hard for the first exam and is irrelevant once passed. The Human Performance exam is too easy (and probably irrelevant for PPL level). As an instructor, the biggest grief of my life (weather excepted) is students failing to keep up their written exams in parallel with their flying. I.e. ready to go solo but air law not passed. Ready for Nav Solo but R/T or Met or Nav not passed.
Of all of these the Air LAw is the worst, hardest and most irrelevant (with exception of rules of the air and licence privileges). Airspace should be covered as part of nav, and all the w@nky elements of JAR/ICAO interantional flights dumped all together. It is a real tragedy to see highly motivated students drifting away during their study for air law...knowing they cannot go solo without it (at our school). I know some clubs do not have this restriction...but are ultimately playing with fire if things go tits up on a solo.