I send my bloods up to Auckland, via the post, to the national testing centre, which is about 6 hours away, we get our levels bac in a week, sometimes less. 2-3 weeks is just slack to me.
We only see the official PKU clinic once a year as adults, about every 3 to 6 months as children because the clinic has to travel throughout NZ to the big cities. But most PKU people I know of tend to have a year-round dietition that they see as once a year isn't enough to keep on track with the diet. And seeing that dietition doesn't cost us anything.