Remember kids... always wear a helmet. (The almighty bikeradar helmet thread)

As for hours per test passed, 45 is reasonable, I've got people a pass on 25 but it's rare and usually quite intensive. Average would probably be about 35-40.
The driving test is a lot about nerves as well, which in a way means the people that care less can do better. Some of the most cautious drivers I've taught have taken the longest to pass because they are scared shitless about the road, the test and everything in between, they were generally who I would consider the most considerate (if not "best") drivers. The cocky twat 18 year olds who pass first time could probably do with more instruction.
I like the idea of a minimum amount of professional instruction as it means that even if some twat is good enough to pass a test they still have to take on board everything else. (It would have also made me a bunch more money as a driving instructor).

Nervous as befuck. Took me from September last year to August this year, at least 45 lessons. Took test twice, 6 minor failed on reverse around corner first time, second time 4 minor faults and a pass.

Still a bit nervous when I need to drive, slowly getting better. Just taking your eyes of the road/in wrong direction or bad luck (you check blindspot to change lane, some idiot decides to cross, cut in front just that moment) and voila. But being too danger aware can paralyze you.