The FAA PPL written is several weeks revision, starting from a relatively recent JAA PPL holder position.
I was on an intensive JAA PPL course in the US and they gave twos day intensive study for the FAA written exam, then sent us to sit the test about a week later. There were probably about 8 students, I don't know if anyone had their PPL yet, but I think everyone who took it passed.
Obviously a very bright but jobless individual with no life can do it much quicker but the above figures are for someone with a job and some sort of life at home, and 100% support from spouse/partner
i admit i didn't have a job
(having a life, that's a question of definition), but i think most of the other people did...