hmm.....think 'bell curve' - with 45 hrs (40 in Oz) being at a rather thin end of the curve. At least those few who are at that end of the curve aren't being restrained by having the 'average' experience at licence issue specified as the mandatory minimum.
My experience has been anywhere from 50 to 70 hours. Biggest 3 effects on it were frequency of lessons, Wx appropriate to the particular flight and age. Mostly frequency though. Discipline to prepare ahead of time also, of course.
Had one fellow get a PPL in Oz in 47 hrs but he had everything going for him.
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Don't mess with the red switches.