It is possible that the average time for a PPL is 2 years but that is only because there are loads of people who had a few lessons in say 1967 and then a few more in 1989 and then finished off when they retired in 2011
I also recall a number of 100+ hour PPL students, of which many or most never finish.
Assuming reasonable availability, which to me means a minimum of one lesson per week, the average time will be 12 months, and this is mostly determined by the weather, and partly by many schools being disorganised and operating unserviceable wreckage. Not to mention bumping prebooked lessons because a bunch of hoodies from the local council estate, with enough body piercings to shift the W&B, booked a pleasure flight (oops I meant to say a "trial lesson"
) which is an atrocious practice which used to happen at one of the schools I was at.
If you could "camp out" next to a school and fly twice a day, you would do it much more quickly - unless you got exceptionally unlucky with the wx. I recall 3 months during my PPL (oct,nov,dec 2000) when I booked a lesson for every day, i.e. ~ 90 lessons, and got just 3 lessons in, due to wx. Warm frontal drizzle, mostly. But people who go to the USA do exactly that: fly 2x a day and at that rate, especially in Arizona, you will be done in 4 weeks.
PPL training can be very frustrating because a lot of flights are cancelled due to haze which is actually lovely flyable wx if you live in the 21st century (GPS) and can instrument fly. The solo x/c flights required in the PPL are
extremely sensitive to haze (most instructors will not let you out solo in < 10k viz) and I recall a number people who lost the whole summer waiting for their QXC, with some dropping the PPL and wasting the £5-10k spent getting there. The whole business really needs an ovehaul... one should be taught dead reckoning but to simply block progress until it is demonstrated on a x/c flight is OTT for this day and age. This becomes painfully obvious to anybody who is fortunate enough, during their PPL training, to accompany a pilot who uses modern methods. But at least those people are more likely to hang in there, knowing that the day after their PPL they can chuck out the silly slide rules etc