I expect (hope!) that most will agree that PPLs should continue to practice their "upper air" skills after they qualify, but my impression is that a large proportion do not. Why? -- well, what is the worst that can happen if you practice stalls, slow flight etc. solo? - answer: you might spin. If I had not had the benefit of spin training when I did my PPL, I would be very wary of solo practice of upper air exercises because I might get into a dangerous manoeuvre that I had no first-hand experience of, and that could conceivably kill me.
In the UK, loss of control accidents now rival CFIT as the biggest killer of GA pilots. A pilot who regularly practices upper-air stuff is unlikely to become a loss-of-control statistic. If every PPL had training in spin recovery, far more weekend pilots would have the confidence to work at their handling skills, and would be safer pilots as a result.
Lets make spinning compulsory again in the PPL!
AD