I have no idea about the statistics, but it seems to be accepted that, the younger you are, the more quickly you learn. Sometimes it can even be shocking how quickly 17 year-olds learn. But, somehow, it does mean that it can be more rewarding teaching more mature pupils.
My 2nd pupil on test is no longer 17 (as is also the case with Rory). She actually started with me a couple of years ago, but combining work with her family and a degree course meant that she found learning to drive just one commitment too much. But moving 10 miles further up the loch meant that learning to drive became a necessity.
Possibly, part of the reason it can harder to learn is that, at 17, people often have less fear and more confidence. Julie's biggest hurdle was her self-confidence. So, although I was confident she was ready for her test, she seemed less so. In fact, in the lessons running up to her test, she made regular comments about 'expecting to fail' and 're-booking her test as soon as she got home after failing'.
She asked me to sit in on the test. An emergency stop right at the start of her test clearly unsettled her and she stalled at the next junction. After a slightly messy couple of minutes, she got it together and began to drive as well as I know she can. But the stall and the messy driving was obviously still on her mind because she seemed completely shocked when the examiner told her she had passed.
Something else that added to Julie's lack of confidence was the fact that she had hardly any private practice outside of her lessons. Seoras was almost the opposite. His parents gave up their time so that he could practice his driving most days. Consequently, his driving became very assured and natural. But, a few bad habits, such as not checking his mirrors adequately, were beginning to creep in. So my job changed from telling him how (and why) to do things, to what could happen if he didn't do these things. As a result, Seoras passed with just a few driver errors, making it three first-time passes out of three tests for my pupils on Wednesday.
The very next day I had another test. This pupil had also benefited from practice with parents and has become a very good, considerate driver. She also asked if I could sit in on her test. It was possibly the most comfortable I have ever felt when sitting in the back. As the test progressed I began thinking that she might complete the test with 0 driver faults. She was approaching a crossroads, with three cars parked on her side of the road, close to the junction. She checked her mirrors and started moving out to pass the cars. Just as she did so, a car turned into our road. She slowed down and the oncoming car slowed too. Unfortunately, she assumed the oncoming car was giving way to her (they probably were) and released her brake. The examiner recorded this as a serious fault and it cost her her test. It was a very split-second decision and, if she had just held back a fraction more than she did, she would have been fine. It just goes to show that EVERYTHING we do when driving should be done to cause as little inconvenience to others as possible.
Bear that last statement in mind when reading the following:
Another pupil, who has his test approaching, was talking to one of his school teachers, who has been having lessons with another instructor. She told my pupil "My instructor said that, on your test, you should slow down and go into first gear at every junction." Now, either my pupil misunderstood his teacher, or his teacher misunderstood her instructor, or her instructor is an idiot....
Imagine if you are following a vehicle and you see that vehicle indicating to turn into a side road. You would probably expect that vehicle to slow to a speed that they could check the junction is clear and negotiate the turn. If that vehicle then slows right down to below walking speed (and selects 1st gear) you will be forced into braking harder than you originally expected. This is potentially dangerous. Sure, some junctions are so tight, or so blind, that 1st gear might be appropriate, but not EVERY junction. And, as a side note, why would you ever do anything different on your test to what you would usually do? (answer: you wouldn't).
As a driver, every day you will encounter other drivers, cyclists and pedestrians that cause you problems. Sometimes it is accidental, often it is due to ignorance, arrogance or stupidity. Whatever decisions you have to make while driving, it should always consider what causes the least problems for others.... And that includes the vehicles behind you who are braking furiously because you unnecessarily selected 1st gear.
Just in case you are left in any doubt, the answer to the question in this post's title is 'Don't be so bloody stupid!'